US Army Ordnance Museum, The Aberdeen Proving Grounds, Maryland
I accidentally went to the museum here after seeing a "brown sign" whilst driving between Baltimore and Philadelphia on the Route 40 North. They have a tiny museum building, with a host of tanks parked outside in the rain (well, it was the day I was there) - looks very much like a complete set of WW2 German and Russian hardware, with a good stock of WW1 and post war stuff as well. Its free, you just have to have ID to get onto the military base on which the museum is located.
The guide says there are 225 parked tanks and artillery - here are pictures of some of them - most are starting to look worse for wear, and there is a collection to build a covered display area (although its very odd being asked to donate money to the US military).
If you are super-dead keen on tanks, email me madfortanks @ madaxeman.com and I'll try to get round to sending you the original photos, which are 500-550kb 1024 x 768 pixel JPEG images from my digital camera. This thumbnail is one of the originals - click on it to see the full size picture:
Must be close to the full set of tank-hunters?
not many '76's around these days...
in the building itself there are lots of guns, but only this one restored french tank.