Hetzner[1]. I never said "in the US", but even in the US you can get a pretty good deal: 16GB for $79/month[2].
[1] http://www.hetzner.de/en/hosting/produkte_rootserver/ex4s
[2] http://www.honelive.com/xml/#new-york-city-dedicated-servers
[1] http://www.hetzner.de/en/hosting/produkte_rootserver/ex4s
[2] http://www.honelive.com/xml/#new-york-city-dedicated-servers
It's 2012 for god's sake, and 32GB RAM servers are still hundreds of dollars a month to rent from any first class data center.
I'm really curious to see how different equivalently priced ASUS and supermicro boards differ.