http://www.rottentomatoes.com/
I was playing around with the tomatometer. Here's the games which have garnered only positive reviews. There's not much depth here; Diablo has only a handful of reviews, for instance. Really, you only want to consider games released since 2000.
Still, though, it's interesting. Here's the top 10 PC games of 2004. The only surprising title on the list is Time of Defiance. However, it's a really interesting title.