Social networks - need to find one? There's rather more than the half a dozen that you can probably bring to mind. Take photography for example - there's about 40 of them. This is where Mamuna comes into play. It's a search engine of social networks - which is to say that it doesn't search a social network, it tells you what's out there which may appeal to you. If you're interested in books or libraries (and why wouldn't you be?) Mamuna provides access to dozens of them. Searches have to be fairly broad, and you may need to be a bit inventive with searches - craft and crafting gave different results, knitting returned yet another result and Ravelry only came up when I searched knit.
As well as a listing of social networking sites there are reviews and background histories for them, and there's also an option to add your own review as well. It's a really interesting site and worth looking at, just to check to see if there's a network for your particular interest.