Then check out the websites associated with each school. All the sites on that page are official Systema schools and a good place to start.
For other Russian martial arts, the american R.O.S.S. site http://www.amerross.com or I think it is now http://www.rmax.tv has a great listing of Russian martial art sites and related things.
The K-Sys site http://www.k-sys.org has a listing of a few RMA sites, but then a great listing of sites devoted to studies that will improve your RMA (or any other martial art for that matter).
And there are of course plenty of Sambo sites around.