A new compatibility update for the Xbox 360 will increase the amount of compatible Xbox titles by 84.
The Holiday comes a little early this year, as the BC team has just issued out another update. The latest backwards compatibility update is now available over Xbox Live (or will be very soon.) This free update brings the complete list of original Xbox games that you can play on your Xbox 360 to over 300. Remember, your original Xbox games will look better than ever on Xbox 360 running in 720p and 1080i with anti-aliasing. You can also play cross-platform between Xbox 360 and the original Xbox over Xbox Live.
More info at Major Nelson, they also have the complete list of the new backwards compatible games.