I like the idea, I'm kinda worried about the site though. It often has too many connections already. And with all the .PNG maps it is bound to take up quite some space as well.
I'm also interested to know the possibilities of linking the database to the league. There could be plenty, but it might just make things more difficult to understand.
Would be cool though, there's some maps that aren't suited for WMDB: ordinary .BIT maps and large packs, they deserve to be stored somewhere as well (and not just on some crappy file-sharing site).
I think it would be cool if you could add a record to each RR-map, allowing users to post their fastest time and a replay of it to prove it. A sort of large-scale RR challenge