Is there a doo-dad I can find to keep a door slighty ajar?

Asked by andrew (16562) October 22nd, 2009 from iPhone

I’m not look for a door jam, but more like a reverse door opener that would open the door slighty if it were close (I’d tape the latch).

I’m going to put the catbox in the front closet, so I don’t want it to be inaccessible in case the door gets closed (since it’s right behind the front door).