Snarl: Growl-like notification system for Windows
Snarl isn't completely new, but the last time Download Squad covered it (in 2007), it wasn't ready for the bigtime. The only notifications available were for iTunes and a clock app. Now it works on apps like Firefox, Pidgin, iTunes, and Windows Live Messenger. Some of the available notification styles are also quite nice, rivaling even Growl's selection.