Snitter is a twitter client built on the Adobe Apollo platform, that means it is a full cross platform application. It has several tabs to get info on yours and your friends and followers tweets.

Features

• highlights messages sent to you via @ syntax (and makes a chirp)
• clear current list of tweets
• refresh list of tweets
• displays last time it tried to request an update (so you know if it crashed for some reason)
• view 20 most recent items in your timeline
• view 20 most recent replies
• view up to 100 friends (most recently updated) and filter by name and screen name
• view and filter followers
• links to easily @reply and Direct message users

Spaz is a free cross-platform Twitter client. It is intended to be a simple, utilitarian desktop app for posting updates to Twitter, as well as viewing updates from friends, followers and the public timeline.

A 'Twitter-like' web server specifically for rumours and gossip.

Autotwit
"AutoTwit takes the effort our of updating Twitter. Simply write a post and schedule an update."

Tweetle
Short URLs for Twitter

Twitter for Apollo (you will need to install Apollo runtime first)
Twitter application for the Adobe Apollo runtime environment