While you can find the site here, it is not a free product on some screens, but removes ads when registering on others. I will figure that out. It but does have tons of features. Mac OSx 10.4 or later is required.
Feature List
* Clean, concise UI with small desktop footprint
* Supports multiple Twitter accounts
* Auto refreshing at user defined intervals
* Replies and direct messages are displayed inline
* Number of unread tweets shown in the Dock
* Delete tweets from Twitter quickly and easily
* Auto show / hide when new tweets arrive
* Control over window layering and priority
* Single click access to user profile pages
* Switch between friend and public tweets easily
* Keyboard shortcuts for list navigation and more
* Control Twitterrific with AppleScript
* Audio notification for new tweets
* Hotkey to show / hide tweets
Filed under: Mac , Twitterific
[...] installed also. You get to choose between Tweetie, Twittelator, Twitterfon, Birdfeed, Twitterena, Twitterific and even [...]