Chad Orzel writes about The Journal of Stuff I Like. Basically, the idea is that you're reading papers anyway; just make a list of the ones you found worthwhile and put it where people can read.
This certainly seems like it could be a useful thing. If you liked one paper I liked, you might like other papers I like.
The dual, of course, would be to compile a list of "people who liked this paper". And from there it's a short step to "people who liked this paper also liked...", and if there's some centralized system keeping track of things, amazon.com-style recommendations, which have on occasion found me books that I liked but wouldn't have known about. (It's a short step conceptually; I'll admit that I don't know too much about how big of a step it is computationally.) But even without these extra steps in the previous paragraph, it could still be worthwhile.
I might start a list. Like I said, it wouldn't be hard. I already have a list of papers I've read, which is reasonably complete over the time period I've been keeping it.