Oops, different names accross the world..

www.hihostels.com (hostelling international up north) http://www.hihostels.com/dba/country-US.en.htm?himap=Y
www.yha.com.au (YHA in Australia..)

The hostel i'm probably thinking of is "Knoxville-Harpers ferry"...I have vague memories of it but isn't there a train from DC to Harpers ferry ....

I also stayed at the one in DC..interesting...