Twitterrific for iPhone is a fantastic, feature-packed iPhone twitter app for beginning and advanced users alike. First of all, their 2.0 release saw a major performance and feature overhaul compared to the original version, which was a great twitter app to begin with. This interface is amazing! It's quick and responsive, and scrolling past a hundred tweets with one flick is no problem. But it's not just looks, because there is a LOT packed under the hood: