The Big List of iPhone Tips and Tricks

I've been collecting iPhone Tips and Tricks for some time now.  The list has gotten large enough that I thought I'd publish it.  Some of these are pretty good, some may not be - YMMV. For ease of use, I've also published this list as a standalone web page.  If you have any not listed here, please post them below and I'll add them to the iPhone Tips web page.

So, in no particular order....

Punctuation/Keyboard Tips

• hit the space bar twice, you get a period.
• Remember
  that the iPhone does not register a key press until you release your
  finger from the screen.  With that in mind, you can quickly get any
  punctuation mark by doing the following, all in one motion: Touch the
  “.?123” key, but don’t lift your finger as the punctuation layout
  appears then slide your finger a half inch onto the period or comma
  key, and release.  The ABC layout returns automatically. You’ve typed a
  period or a comma or any of the punctuation symbols with one finger.  
• To type all in Caps, use the CAPS LOCK feature, make sure it is enabled in the General
  Settings. To use it, simply double-tap on the shift key. The shift key
  will turn blue.
• If you are writing something and the iPhone flags a word as misspelled
  that you know is not misspelled, cancel the correction 3 times and the
  word will be put into the dictionary.

Double- Tapping

• In
  Photos, Google Maps, and Safari (the Web browser), double-tapping zooms
  in on whatever you tap, magnifying it by a factor of two.
• In
  the same programs, as well as Mail, double-tapping means, “restore to
  original size” after you’ve zoomed in. (Weirdly, in Google Maps, you
  use a different gesture to zoom out: tap once with two fingers. That
  gesture appears nowhere else on the iPhone.)
• When you’re watching a video, double-tapping eliminates or restores letterbox bars.
  
• If you double tap a video while it is playing, you will magnify the image so that it fills the entire screen.

Headset "Clicker"

• Pinch once to answer an incoming phone call.
  
• Pinch
  for a couple seconds to dump the call to voicemail. (You can also
  double-tap the Sleep/Wake switch on top of the iPhone to send the call
  to voicemail.)
• During music or video playback, pinch once to pause the music; pinch again to resume playback.
• During music playback, double-pinch to skip to the next song.
• If you aren't using iPod at all and want some music, you can start up iPod mode
  with a double-squeeze then a single squeeze to start the music
  playing. It will automatically start playing the first song in your
  Songs list, and work it's way through.

Customizing the iPod Buttons

• In
  the iPod tap  the More button, and then tap the Edit button (upper-left
  corner). Drag an icon from the top half of the screen downward,
  directly onto the existing icon you want to replace. It lights up to
  show the success of your drag.  When you release your finger, you’ll
  see that the new icon has replaced the old one. Tap Done in the
  upper-right corner.

Misc.

• The iPhone will automatically capitalize the first letter of a new sentence, so don't bother doing it yourself.
• Don’t put apostrophes in contractions - iPhone will do it automatically.
• If you have multiple apps open like Safari, iPod, Youtube, stocks
  etc.,  when you press Home it does NOT actually clear or
  close apps., and this may affect battery usage.  To
  actually close (or Quit) an application, HOLD the Home button for about
  4-8 seconds while in the application.
  

Reset

• Press and hold the Home button for six seconds to force-quit a program that seems to be stuck.
• If
  the entire iPhone locks up press and hold both the Home button and the
  Sleep/Wake switch for eight seconds. The screen go black, and then the
  Apple logo appears as the iPhone reboots.

Phone

• To
  stop an incoming call from ringing, press the sleep / wake button. To
  send the call immediately to VoiceMail, press the sleep / wake button
  twice.
• If you select a photo for a contact from the iPhone, the selected photo is shown full screen for the caller ID.
• If a contacts photo is transferred with the contact's info from the
  Address Book, the contact's photo is shown as a thumbnail for the caller ID.
• Keeping the favorites screen open allows you to unlock the screen then dial with three motions.
• The home button can be used to access unlocking instead of sleep wake.

Email

• To delete email by just swiping left to right on the email in the list and press the delete button that pops up on the right.
• If you want to save a message you’re working on so you can come back to
  it later, tap Cancel. Instead of deleting the message immediately, Mail
  pops up a dialog asking you to Save, Don’t Save, or Cancel. Tap Save
  and the message is placed in your Drafts folder. If your account
  doesn’t currently have a Drafts folder, Mail will create one.

Google Maps

• Typing
  in the three letter airport code while in maps will bring the airport
  up on the map. So if you are trying to view a map of central NJ, Typing
  EWR  will bring up the Newark airport. It's relatively quick to zoom
  out, recenter over New York, and zoom in again. It seems to recognize
  all primary and secondary US airports and many overseas airports as
  well. Here's a Link to find airport codes.  
• Tapping on the address in your contacts opens it up in Google maps.
• You
  can send yourself a link (via email) to a map from Google Maps online -
  when you click on that link it will open in Google Maps (not Safari). 
  If you have a bunch of locations you want to save send email links and
  save them in an email folder.

Safari

• When
  you've scrolled down to the bottom of a page, and you want to go back
  to the top- just tap on the top bar of the phone (where "AT&T" and
  the time are) and the page jumps right back up to the beginning.
• If you want to scroll inside text area form fields and scrollable areas in a page, use two fingers to scroll.
• To email a page to someone tap on the address bar. The Share button on the top left will create a message for you.
• Page
  down. When not using a zoomed-in display, double-tap towards the bottom
  of the screen. The page will re-center around your tap. 
• Zoom
  onto a single picture. Double-tapping images in Safari zooms them to
  fit your iPhone display. If the picture is linked to a URL, this can
  prove a little tricky but it works great for non-linked images.
  Double-tap again to return to the unzoomed display.
• Zoom a
  column. You can zoom text columns as well as pictures. Double-tap on
  the column to fit it to the display. Double-tap again to return out of
  the zoom. Not only does Safari zoom block-quoted text independently of
  regular text but if you move your finger after the first
  double-tap-to-fit, it interprets the next double-tap as a re-center
  page command rather than a return-to-previous-zoom.
• Stopping a
  scroll. After flicking a page to get it to scroll, you can tap the page
  at any time to stop that movement. Don't forget, you can also manually
  drag the screen display to reset the part you're viewing.
• Manual
  zoom. To zoom into a Safari page, put your thumb and forefinger on the
  screen and move them apart. To zoom out, pinch the fingers together
  after starting with them apart.
• Examining the URL. To peek at a
  link's destination, touch and hold the link for a few seconds. You can
  also do this with images to see if they are linked. If a link appears
  and you don't want to activate it, just slide your finger away until
  the destination text disappears.
• Google Videos.  Point your
  iPhone browser to a video on google video and choose download for
  iPod/PSP and you can watch it right there in safari. 
• Bookmarks:
  Create a separate folder / section for all your iPhone web sites. This
  makes is easy to locate them while browsing the we on your iPhone. 
• RSS. If your favorite 'news' sites offer an RSS feed, bookmark and use that
  on your iPhone (I have an "all RSS" bookmark folder to collect them). This can make browsing,
  even while on EDGE much faster.
• You can get on the internet during a call! You can only do this if your
  connected to a WIFI network (it wont work via edge), just hit the home
  key and click on Safari. Now your surfing while talking! The person on
  the other end can't hear the keyboard clicks either!

Address Book

• Create several subgroups, this can speed up the location of a contact given the lack of an actual search function.
  

Notes Hack

• Since
  the Notes cannot be manipulated on the desktop (yet), you can hack your
  way aound this to have notes that can be modified on your desktop: (1)
  create a new address book group called 'Notes'; (2) create a dummy
  address and give it company name "Notes" (3) populate the "Note" field
  of this contact entry with plain text This will now sync between
  multiple Macs/PCs and always be available on
  iPhone, even when it is offline. Simply look in the address group Notes
  for these items - not ideal but it works

Clock

• When the alarm wakes you up in the morning, touching the
  sleep/wake button will "snooze" and sliding the wake up slider will
  turn off the alarm.

Camera

• To get  better picture, press and hold the
  shutter button.  As long as you are holding the button, you can set up
  the picture.  When you release the button, the picture will be taken.

Stocks

• If you touch the green/red boxes outlining the +/- movement of the stocks, it changes to displaying the %.

Weather

• Click on the yahoo link on the bottom left and safari will launch into Yahoo city guide.

iPhoto (Mac Application)

• The phone shows up in iPhoto by default.  To disable this, turn off in image capture
• You can use 'Camera is not Apple iPhone' in a smart playlist
• A contacts picture folder /album is a good idea
• A wallpaper folder / album is a good idea - Create an Album (folder) called iPhone Wallpaper and load up your
  favorite 320x480 wallpapers. This makes it very easy to pick a new
  wallpaper on your iPhone.