I've just posted a note to JESSE, the listserv for library/info science educators, hoping to get a Ravelry meet up at this year's ALISE. There is at least one paper on the Ravelry community being presented at this year's conference, which sounds like a perfect reason for a meet up!
Ravelry is a wonderfully rich community of knitters/crocheters/spinners/weavers. The software allows stunning integration of conversation and old-fashioned hypertext! Why describe a project when you can show it and indicate the pattern, yarn, needles, and general enjoyment of making it? Others can comment on it, 'fav' it, add it to their project queue. There's a library of books and patterns. Stashes of yarn are shown - making them available for oohing/aahing as well as swapping.
And did I mention the groups? There's a group for everyone! Communities know no bounds.
But Ravelry is a gated community. Free admission. Very little delay. But it is not out in the open Web for everyone to read. I admit that my Web blogs are suffering due to my Ravelry involvement.
Are there other communities like Ravelry? I haven't heard of any. Ravelry answered a need, and I think has been a major force in getting this niche community online and connected.