Hummingbird is an intelligent Twitter marketing tool. It targets and auto follows Twitter accounts based on keywords. It also provides stats and reports of your account, followers, and interested tweets.
As an Adobe Air app, Hummingbird supports Windows and Mac OSX (it should support Linux though it’s not written in Hummingbird website. Strange uh?). One cool feature of Hummingbird is that it supports 3rd party plugins and most of them are free. Unfortunately Hummingbird itself is not free and kinda expensive.. 197$! and there’s not trial version to test.. At least the screenshots shows some of the mentioned features.