Would you mind naming some good chess engines for Mac, Windows and Linux? (I know this can be googled, but I value the recommendation from a credible source).
The Stockfish team has made tremendous progress recently, thanks to 1) putting the code on Github and accepting patches, and 2) building an open, distributed testing framework that tests every patch by playing thousands of games.
A cool feature people may not know about - many of these GUIs allow you to play two engines against each other. It's fun to watch two strong programs slug it out. :)
Stockfish is amazingly strong. It's the world's second strongest engine (after Houdini) and completely free and open source. On average modern hardware (say core i7 CPU) it's rated around 3250 ELO.
I also have HIARCS chess (rated 3190 ELO on my hardware) which is notable for its human like play, but Stockfish kills it almost every single time.
