An idea. Take out classifieds on myspace with your interests (the niche) in the headline. Since the classifieds are free, you can find 10 - 20 highly populated cities like Los Angeles, New York, etc.
Not knowing what your niche is, I can't be more specific but let's say it was automotive related, you could say something like "Mustang Owners/Lovers Myspace Group" then in the add say something like:
Looking for people who drive, want to drive or just love the Ford Mustang who want to share photos, info and so on. Add me!
There is a site that adds friends for myspace games. Off the top of my head I can't remember the name of the site but it's probably somewhere in the myspace forums on here. It's like a friend train for the myspace games. Anyway, I was using it for ewhoring and added about 100 friends per day. My account was deleted but I think that's because I was ewhoring and using vacation response on myspace to send people to my "adult site"
