Yeah, now that I've used KillMe a couple more times recently, I'm not so sure it's as good as simply force-quitting the app.
You type in the item that you want to force quit, and it gives you a "success" message.
On a hunch though, I typed in random letters, and hit submit. It still gave me the "success" message!
I think it would be better if it would either give you an "unsuccessful" message if you truly do not have anything by that name running, or if it would give you a list of things to cancel, based on what you type.