We know how big a community can be - Dunbar's number tells us that (150). But how small can a community be and still have any functional significance? The Wisdom of Crowds suggests that a community needs a reasonable size to have any analytical power, but how small is too small?
The reason I ask is because the journal Retrovirology just started a blog. I have subscribed, but with all the competing information we struggle with, is a blog about one journal focussed on one family of viruses is just too small to build a powerful user community?