Have just spent the past hour browsing
ship_manifesto, which is a series of essays (of, from what I've read so far, unremittingly high quality) each expounding the virtues of a particular fandom pairing (both gay and het, canon and non). They've just finished their first chunk of the Buffyverse, and if you go back to the start of the community (only a page back) you can see the upcoming schedule for other fandoms/pairings.