Knitting Help is unique as far as I can tell. It's devoted to knitting help. The crochet forum gets used but not as much. I think Sheldon said they are going to work on developing the crochet forum more and having a crochet pattern directory too. I expect there will also be crochet videos. One thing I noticed at one of the main forums is that crochet and knitting are all lumped together and you might think a question is about knitting and find as you read that it's about crochet. That's IMO not helpful and is inconvenient. I hope that the two stay separated here; crochet is good and I've done a lot of it and if I need or can give help I want to have a place to go that's for crochet. We can stray off topic here without getting our virtual wrists slapped and I like that. Camaraderie among members is nice. The size of ravelry alone is off putting to me.
I should never overestimate my basic arithmetic skills.