Moonlight is the story of Mick St. John, an 85-year-old vampire, trying his hardest to not be too much of a vampire. He has his boundaries, rules that he lives by. He doesn't hunt women, children or the innocent. But he does deal with the predators out there that prey on the helpless or unsuspecting.
mickbeth_daily Drabble community that's not really active anymore but the mod is trying to drum up participants.
ml_btvs: Moonlight/Buffy the Vampire Slayer crossovers
ml_fic_digest not updated but there's a host of moonlight fanfic links.
smallfandomfest: a site that has fests to celebrate small fandoms including Moonlight.
galorechallenge: crossover challenge community that accepts Moonlight
Essays/Ship Meta(so far I haven't been able to find one on Mick/Beth but when I do I'll add them)
He Promised to Love Her Forever: a Mick/Coraline Essay
True Love is Immortal: Josef Kostan/Mick St John
The following are some sites off of livejournal that you might like:
Transcripts, Episode Guide, Screencaps and etc..
Moonlight on Archive of Our Own
Moonlight Fanfiction Archive
Updated: March 21st, 2012
If I've missed something please let me know and I'll add it to the list :)