JavaScript Chess
I was testing out some Chess programs to use here. One I came across was open source: JavaScript Chess. In testing it I was very impressed with the CPU play as well as the simple animations moving the pieces. My only regret is that near the end game this pop-up window came up with debug info so there are bugs to be worked out.
Javascript Chess (Hover)
Javascript Chess Description
Play in your Firefox browser, no installation necessary, or upload to your server and play with a far-away friend. Games can be saved to a database and/or a simple text file. Includes a simple PHP mysql script for database connection.
Utilizes bitboards (arrays of two 32-bit numbers) and lookup tables for fast move-generation and analysis. Endings include checkmate and resignation; draws are yet to be implemented. The cpu engine is a work in progress, suggestions/contributions are welcome. Can log static-exchange stats and be configured for more.
The interface does look nice, that's what first attracted me to it but it is useless if you can't play a game of chess properly. The other element is JavaScript is very unstable at times especially with browser updates or browser versions.