I'm a huge racing fan. I usually play every weekend. I go to Belmont a few times a year. I go to the Spa at least 6 days a meet. This board is one of the best I've seen on the internet.
http://www.paceadvantage.com/forum/index.php? Is a decent board with some interesting banter.
The best board in terms of New York racing is NY Racing Community.
http://www.racedayny.com/index.php