For iPhone odds calculators, I have PkrCruncher, Poker %, and HoldemEval. PkrCruncher is the best of them I think, but Poker % has some flashy features if a non-intuitive interface. Holdem Eval isn't pretty but it's quick & easy to use.
Then I have a few other random apps in my Poker folder, including the official WSOP
game, a tourny management app, the PokerNearMe app which finds poker rooms near your location, the PPA app, a bookmarked icon to go straight to CardsChat, etc.
I also have the HM2 app. If you use the cloud sync feature of HM2, you can use the mobile app to review hands while away from the computer, share hands with friends who also have the app, access poker & HM news/videos/articles, etc.