Now one thing I like about Apple programmes is that most are contained in that single .app file. To uninstall, simply move that to the trash. However, unbeknownst to you, many also create files scattered about your hard drive, and when you delete the .app file, it does not delete these files.
AppTrap (when running) detects when you send a .app file to the trash and asks you if you want to delete the other system files associated with that app. A nice little cleanup preference pane to help keep things tidy.