Windows only: Lifehacker reader Jeff used his ubergeeky desktop customisation skills to create a Rainmeter config that updates your Twitter status directly from the desktop.
Setting up the same configuration for yourself requires installing Rainmeter, unzipping the SendTweet config into the Skins folder, customising the script to add your own Twitter username and password, and then launching SendTweet from the Rainmeter system tray icon. Once completed, you can simply click the textbox and start sending tweets directly from the desktop.
Readers will note that like most Rainmeter configurations, you should probably read through the config files—and if you installed Rainmeter into a directory other than the default you will have to adjust the paths in the included SendTweet.ini and RainInput.cfg files. You can drag SendTweet anywhere on the desktop that you would like, but you will need to update the RainInput.cfg file with the correct position for the text box to make sure they match up. If you are willing to roll up your sleeves and do a little tweaking, it's an excellent addition to your own killer desktop. Great job, Jeff!
SendTweet is a free download, requires Rainmeter on Windows.