Are you so addicted to RSS, Mail, and Twitterrific that you just can't stand when your screen saver launches? Status Screen Saver might just be the screen saver for you. The awesome thing about this screen saver is that is displays your current unread Mail count, unread NetNewsWire feeds, and even unread tweets from Twitterrific. You can select a screen saver that you have installed in the Status Screen Saver options.
Even better, Status Screen Saver allows you to (with some AppleScripting) create your own "modules" which opens up unlimited possibilities to what can be shown in Status Screen Saver. So, if you use something other than the supported applications, you can (if the application is scriptable) make an AppleScript to give a number, then place it in the Screen Saver.saver/Contents/Resources/ directory.
Overall, this is a really cool screen saver which can be expanded upon by the user. You can download this free (donations accepted) screen saver by visiting the developer's website.