TweetDeck for Adobe AIR is a cross-platform Twitter client that uses a multi-column view to customise its look and feel. The iPhone version of the tool works in much the same way and the hugely flexible dashboard makes it possible to view as much or as little information as you want.
If you have the AIR version of the program installed it is possible to sync settings between the two for a uniform Twitter experienceand the app's handling of message allows for easy interaction. The message stream can supply notifications when new tweets are received, and upon viewing individual tweets simple links for replying, direct messaging and retweeting make it easy to work with.
Images attached to messages can be automatically uploaded to the likes of Twitpic and YFrog and URL are automatically shortened using the service of your preference. Customisable columns for trends and saved searches can be used to keep track of tweets relating to a particular subject and the multi-column interface allows for quick and easy movement between different aspects of the app.
It is rare for a desktop application to make a successful transition to the small screen, but TweetDeck achieves it will aplomb.