Here are the semi-thought out game ideas I've had recently that have held up to the 24 hour test. I figure if an idea sticks with me for more than a day it might have something of use in it.
White Collar Robots - The game of robots standing in for their white collar, office counterparts.
Planet Crash - A Game Chef attempt using the keywords city, edge and desert. After crashing in a deserted city floating at the edge of known space the character experience what happened to the original citizens.
The Island - (Yeah, I know. It's not an original title once you read the theme.) The characters get stranded on an island. They can't get off until they solve the mystery of the island in spite of the secrets they keep from another. The idea was inspired by Lost but after thinking about mechanics I think it could be played zany like Gilligan's Island.
Those are the biggest three game ideas I've had that seem to keep haunting me.