Update: The site seems to be alive and kicking. Great list there. Check it out!
There used to be a great list of unit test frameworks at http://www.xprogramming.com/software.htm . The site seems to be dead now. I wonder what happened. It's a sad thing when good resources suddenly "die".
There's another list (I think it's not as extensive as the one that died) over here on wikipedia:
http://en.wikipedia.org/wiki/List_of_unit_testing_frameworks