community_promo, which allows LiveJournals users to run promotions for both the communities they maintain, and the communities they like the best. It is a great place to spread the word about your favorite communities, and to learn about some of the more obscure ones that slip under the radar.However, there's another great place like
community_promo that'll help you find some great communities. I'd like to announce the recently sanctioned resource community_quest, a community where you can post and try to find communities that already exist. Try it out! Its run by the same maintainer as community_promo, and is quickly becoming the most popular way to find what you're looking for. Its the 411 of LiveJournal communities!