http://www.livinghistoryworldwide.com/
Since my historical re-enactment exceeds most living history groups (such as the SCA and the Civil War Re-enactors and the Colonial America Re-enactors and the Rendezvousers), this may be a decent group. Pity they don't have any future history re-enactors.
I'm checking it out, anyway.
And for Retro American fun from the 50's, there's http://www.timewarpliving.com