Slash archives? (It's not for me... this time...)

One of my iSchool compatriots is curious about the proportion of fanfiction, particularly slash, that disappears from the world unnoticed and unmourned. She's looking for more info on people or groups who are making attempts to archive slash, what form that takes, and how long those archives last. Any long-term archive links for us?

I'm now curious as to whether the more successful archives are fandom-specific or omnivorous collectors. Also, what are the permissions issues? I mean, none of this can be "claimed" in court, but what are the social ethics of collecting - would it be permissible to grab the contents of another archive without the permission of the individual authors?

(For the two people reading my journal who are unaware of slash, it's fan stories about established fictional characters from TV or books, usually sexually explicit, usually homosexual. I figured you'd rather hear it here than google it and scald your eyes.)