I keep coming back to TiPb because of the dedicated coverage of all things iPhone, iPad, iPod and iOS. There are a lot of other great sites out there, but a lot of them a filled with a lot of information about other products that I don't care too much about.
The tips and journalism are great and keep me coming back many times per day. I have the twitter feed open on my second monitor on my Mac so I can always see any new juicy tidbits as they get posted.
Great job guys (and gals)! Keep it up! I'm looking forward to this summer with all the new iOS 5 and iPhone 5 coverage.