I had a quick peek at AO3 to see if my favorite writers from when I was still reading LotR were there, but couldn't find any of them, and I don't know where their stuff might be archived nowadays. I just had a quick look through my Delicious tags, because I know there's at least one LotR-specific fic archive, possibly two or three that I'd run across, but evidently I was browsing there before I had a Delicious account. The only good link I turned up was to the Bagenders, which is a comedy series.