Scid can perform many different searches, such as for particular players, a
certain opening position, material searches, and pattern searches such as
isolated pawns. It is very fast, because it uses its own efficient format, but
it can convert games to and from PGN, the standard format for chess game files.
Scid can use a chess engine such as Crafty to analyze games and also has a
"tree" mode where it automatically shows all moves played from the current
position, their opening codes, success rates, etc.