The Suppressed Transmissions Google+ Community
If anyone here is on Google+, check out the Suppressed Transmissions Community there which I created last year.
The kind of stuff that's prime fodder for the Arcana Wiki pops up there regularly, and in fact I've added more than a few articles mentioned there to the wiki.
The Spambot Death Wall
Arcana Wiki - Distilling the Real World for Gaming
Urbis - A World of Cities - an urban fantasy setting of industrial magic
LiveJournal