Matching services for friends?

Robin Hanson asks "Why Not Friend Match?" I.e. why are there dating sites but not friend sites?

That isn't to say that there aren't friend matching sites (e.g. here, and here, not to mention  Facebook), but nevertheless his conjecture strikes me as plausible: we (at least initially) draw our friends from the people and places we encounter for other reasons, since friends complement our other activities. Or, as he puts it:

"Since we need friends in substantial part to serve as allies in our social world, supporting us against opposing coalitions, it makes sense to draw our friends from our existing social world. And since we need mates more for their personal quality, e.g., good genes, youth, wealth, smarts, mood, etc., it makes sense to pick them more via such features."