Does anyone know if there's a database to search for related positions?  I have played lots of games where, at some point in the game, I say "Hey, I just saw a game like that somewhere!"  Is there any site to find games that look like yours?

Ideally, it would be a website where you could type in keywords: "Bad dark-square black bishop, e4-d5 pawn chain, loose knight on a4..."

thx.

You can search for partial positions, or certain elements within a position using ChessBase 10.

I think you can find something in www.chessbase.com.