What I mean is, have you ever set up friends to meet each other as friends only, when you know two people who might be a good friendship fit? I can't stay I've purposely set up friends thinking that they'd get along, but I did get a big group of them together once in hopes that a few of them would become friendly. Sometimes you're friends with people who need more friends, or who have different interests than you.
When some of my friends started getting married, for example, a few of them introduced me to a couple of their single friends. This was because I was still single and it was nice to have a few single buddies to go out with.
I think friend set ups are a really nice thing to do for people, but it can be tricky (just like it can when you set people up for a romantic date). You have to do it the right way, otherwise you might alienate your friend or hurt their feelings. Here's my advice on setting up friends.