Growl

Last fall I made a post agitating for a standardized notification framework for OS X. I recently discovered that others had been thinking similar thoughts around the same time and earlier. Since then, I've adopted Growl as my notification framework of choice. Version 0.6 (now at 0.6.1 actually) was released a few days ago, with a number of nice improvements. I've been using it for a while and heartily recommend it. (For the devoted, it's not hard to track the development version if you have Xcode and a Subversion client.)