Warcraft Chest will let you look at drops from all bosses in dungeons and raids, rep rewards, Badge items, and PvP rewards. So if you want to drool over your favorite items while away from the game, it'll let you do just that. Unfortunately, the interface is a little boring, as it's just your normal iPhone app; it would be nice to see some kind of Loot List functionality, where you could sort items by class or type. But if you're invited to a Heroic and want to see what drops in there without alt-tabbing out of your game, there you go.
And WoWTalent will do the same thing for class talents -- you can browse through all the talent specs of every class, including all the Hunter pets and the various talents that come with each tree there. You can load and save trees to show your friends later, but unfortunately, there's no way right now to share them online -- the WoWHead talent trees are pretty URL-hackable, and it would be nice to be able to export a tree you create in WoWTalent out to a URL you can email or even tweet. But for browsing talents away from the game on the iPhone, it too works. As I said, both apps are free and available now.