Most useful apps: Grooveshark - any song, anytime. I've stopped using the iPod feature on my phone. This costs like $2 a month or something. Better than Pandora because it also has a "radio" function which is great and gives a lot of good recs. But that isn't even the main draw. You also need to be jailbroken. SlingPlayer Mobile - watch all your tv stations live, streaming. Costs $30 unless you are jailbroken. Also requires you have or buy a slingbox for your home. NYTimes - Finally, something useful to do on the subway. Catch up on all the latest news from an actual reputable source. Allows for fast full-downloads of ALL articles for later offline viewing. GVMobile and TextNow - If you have a Google Voice account, these are great. GVMobile requires jailbreak. Textnow allows for FREE texting. Weather Channel - Much better than native weather app. MyWi - Requires jailbreak. Use your phone for tethering (provide wireless to your laptop through your phone). Skype - Free/dirt cheap international calling. If jailbroken, you can use anwyehre not just wifi. 3g Unrestrictor - Jailbreak only. Allows you to use SlingPlayer and Skype in Edge or 3G locations. WordsWithFriends - The only game I play. It is Scrabble for the iPhone with a huge network of existing players of all skill levels. And of course the most important apps of all: Backgrounder - Jailbreak only. Without this your phone is useless. Allows multitasking of an unlimited number of apps. SbSettings - Allows for quick one-swipe access from any screen to a dashboard that controls brightness, rotation toggle, wi-fi, airplane mode, 3G, Edge, Bluetooth, Process Manager (i.e. Task Manager on Windows - also allows you to clear RAM), numeric battery, Ram usage display, etc. That just about covers it. If not clear from the above, a jailbroken iPhone is the only one worth having. But don't do it unless you know what you are doing.