[Robertie]

The best site for your purposes is GamesGrid, and I would recommend paying the few dollars a month it costs to play there. The ratings are accurate and many good players play there under their own names or aliases that are easily recognizable.

The ratings on GamesGrid are equivalent to the ratings that Snowie would give you. I don't know about Gnu but I imagine the ratings are similar. Most top players maintain ratings in the 1900s. Ratings higher than that are either a statistical fluke based on a recent winning streak, or the result of combining Nackgammon play with regular play. (Nackgammon is a variation of BG in which the skill differential manifests itself faster, so if you are good and play a lot of Nackgammon relative to regular BG, you can inflate your rating somewhat.)

Until you are truly a 1900+ player, don't try to play for high stakes ($20+ per point). There are plenty of sharks laying in wait and you'll get slaughtered.