I paid for AppZapper and it has some nice flashing effects and a killer "Zeeoooo!!!" sound, but it really is, for all intents and purposes, in the words of another anti-Delicious-Library-generation developer just a spotlight wrapper with nice snazzy effects.
What I am really looking for is an app that hooks into the OS and monitors file activity as apps work. Some apps have some funky trial periods and they write some secret stuff into your system SOMEWHERE which you can perfectly remove short of a total nuke and reinstalling your entire operating system.