There was a fansite already devoted to the Dumbledore/Grindelwald pairing. grindeldore These folks are dancing in the aisles. And there is already fic and art.
I really enjoyed these drawings:
http://slytherinfiend.livejournal.com/54683.html Happy Outing Day byslytherinfiend
and this total charmer:
http://community.livejournal.com/grindeldore/10622.html by fabledtruant
Addendum: And this was really interesting. A chat on the Washington Post with Melissa Anelli, who runs The Leaky Cauldron website. Apparently she talks with JK Rowling. I thought she made a lot of good points:
Ah, it's enough to make one want to jump on the bandwagon. Er . . . maybe not.
(If the links won't work, just copy and paste and they will. LJ is giving me MAJOR crap today. And if anyone can tell me why neither the insert/edit link or html code works any more on my LJ to hide long URLs, and why LJ won't put the links in if I also have LJ user links in the same post, I 'd love to know.)