I currently belong to 80 communities. Some of my favourites (i.e. ones that I am pleased to see crop up on my reading page and to read posts from, even if the subject matter for some might not be jolly or happy) are _survivors_, ae_stories, crowdfunding, migraines, shadowunitfans, unusual_minds, nonidiotswithms, introverts and quirkyalone.
The question I answered here, in case they change it (which they have done before), was, "What are your favorite LJ communities?" (sic)