Capster is a Caps Lock notification tool for OS X, which uses Growl to notify the user when Caps Lock is pressed, to help in case of accidental click.
The idea is borrowed from CapSee, but it is slightly faster, and uses Growl for notifications instead of creating a Bezel in the middle of the screen.

It is released under a FreeBSD license. You can download the executable at the project's home page.
Direct download link: http://www.tzikis.com/capster/Capster.zip