I thought I'd bookmarked this site but ...
There is, somewhere on the intarweb, a name site that some kind soul created that is an auto-generated naming list based on modern american census names.
You can either leave first and last name blank, and it will generate both, or you can put in a first name and get a list of last names etc.
I find it really, really useful. Or I did before I lost it. Anyone know what I'm talking about?
EDIT: Thanks Everyone - those were great resources! The particular site I was looking for is this: http://www.kleimo.com/random/name.cfm