I picked this up from @RobinRWrites on Twitter. I haven’t investigated it, but it looks so promising, I have to share it. Mythicscribes.com has a forum, and they’ve set it up to promote writing-related blogs by people who leave substantive comments on their forum.
I’ve just discovered Mythic Scribes, and know nothing about them, but their announcement says their top posts get thousands of views per day. It’s too good an opportunity not to look into. If you try it out, my advice is that headline strength is very important for this sort of promotion.