AppTrap
Everyone loves AppZapper for removing unwanted applications, and while many have called for something like it to be included in future versions of OS X, AppTrap comes closer to replicating the Mac simplicity we all enjoy so much. Expanding on the drag-and-drop workflow used to install programs, simply drag the unused application to the trash, and AppTrap pops up asking if you'd also like to delete any associated files.
AppTrap is free, open source, and installed as a system preference pane.
