Birdbrain is an iPhone/iPod touch app that monitors your Twitter network for changes. It provides daily, weekly and monthly overviews of your friends like who is new and who left. It supports also multiple accounts.
The application is not considered as a Twitter client, but a complementary app. The app is not free for $1.99 and available in the AppStore here.
Pros & Cons
|Provides different functionality than others Twitter iPhone apps|