The well-known macro application Keyboard Maestro has been updated to version 3 and adds some interesting new features. In addition to a revamped interface, the new release allows you to record macros (series of key presses, mouse clicks, etc.) and play them back via various triggers. There are also new ways to trigger the macros; besides the normal hotkeys, macros can also be triggered with AppleScripts and even remotely with Keyboard Maestro's built-in web server. If you've ever wanted to automate your Mac, it's definitely worth a look.
Keyboard Maestro 3.0 is $36 with upgrade pricing from $18 - $26 for previous users; a demo is available.