Comprehensive information about the US rugby scene can be found at
www.usarugby.org/default.asp, the governing body of American Rugby Union. Not sure exactly what contact with this august body might achieve but I'm sure that it'd love to hear of your support in what must be one of its own main endeavours.
If you really want to start at the top - or bottom depending on the way you think trees grow -
www.irb.com is the world's sometimes unloved and often unloving governing body.
If you really want to see what it's all about, find a local club with a good junior section and go to see the kids play. It's where all the heroes of the RWC probably began their playing careers and, if its anything like my own club, Sunday mornings alone are enough to give you hope for mankind!
I guess that it's now back to the subject of sailing - until, of course, the Six Nations!