http://www.robofest.net/
We did the 2009 competition in robofest with our FLL team, nice break, end of the year event, simple games, no project.
You could look up a few years, all the games are played with household items, on a banquet table. (hint, start with the table legs folded on the floor, $300 nxt's survive 2" drops better than 30" drops.)