http://www.iphoneheat.com/2009/06/best-tips-for-iphone-os-30-mega-post/
How to Create Voice Memos
How to enable Tethering with Mobile Safari
How to send MMS
How to enable Video Camera feature in iPhone 2G and 3G
Account Management and Video Uploading to YouTube
How to Use Copy/Cut/Paste/Delete Feature
How to Show Battery in Percentage
How to Control Battery Drainage in iPhone OS 3.0
Patch MobileInstallation on iPhone OS 3.0
How to Use Find My iPhone Service and Remote Wipe [iPhone OS 3.0]
Delete or Forward Individual Messages
Type new message while previous is still sending
Text Message Sending Failed (with Exclamation Sign)
How to Share Contacts
Email Photos (Up to 5)
Shake to Undo and Redo Typing
Swipe to delete note in Notes
Shake to shuffle
Copying and Pasting Photos and Videos
How to Use Voice Control (iPhone 3G S)
How to Force Quit An Application
Landscape Keyboard
Double clicking Home button
Call history log
Copy or Open Link in New Page in Safari
Auto-Fill User Name and Passwords
Spotlight Search
How to Search Through Emails
How to Search Through Notes
How to Search Through iPod
Execute Application from Spotlight
Install Practically Unlimited Apps
Count your Installed Application
Safari
Moving app across pages
How to use Parental Controls
Updated App Store View
How to Sync Notes with iTunes
How to Encrypt iPhone Back Up
In-App Purchasing
Peer-to-Peer Connectivity
Purchasing and Downloading Content from the iTunes Store to iPhone over 3G Network (no size limit)
Turn By Turn Navigation
Playback audiobooks in variable speeds
Calls from non-contacts shows city and State/Country
Album Art Displayed While Charging (instead of battery logo)
http://www.iphoneheat.com/2009/06/best-tips-for-iphone-os-30-mega-post/