This provides trends of what people are saying on Twitter just like Google Trends does for internet search words.

Twitturly is a service for tracking what URLs people are talking about as they talk about them on Twitter.

Another Twitter client for your iPhone.

This is an open source Twitter client for iphones.

Second Gear creates beautiful Mac OS X desktop applications: Today for tracking your daily schedule; Check Off for keeping your todo list.

A Java-based Twitter client compatible with more than 200 kinds of mobile phones.

Twitter client for Windows Mobile. Not as cool as the iPhone versions, but then again, what is?

Send updates from your 30boxes calendar to your mobile phone using Twitter.

You can update Twitter from your mobile phone using this service.

Qik is a mobile utility that enables anyone to share live video from their mobile phones with their friends, family and the entire world.