The Twitter widget is a desktop twitter client build upon the Yahoo Widget Engine. It looks like this (click for bigger image):
Different skins. Also in in white
NEW! Version 2 is in BETA: check this new screenshots:
What it does: Everything. But a betaish everything for now.
It works on Windows and Mac (OSX).
Read the help (especially the 70-api-calls-per-hour part). Ask questions here.
2. Download the Twitter Widget here.
If something blows up, it's your fault. It's always your fault.
Future features (say that really fast): more eye candy, archive, groups, more options.