In your case I actually think Craig's List/ Community listings would work. They are generally populated with ads for lost dogs & cats and musicians looking for bands. -Anthony
My current network is the sixth I've built at Ning (deleted the others when Ning began charging for use of their platform), but each time I had a plan. With any social community, it's best to have a strategy before you start. Saves time, money and work. For most of us, we have relationships outside of our networks that we then bring on board once we've set up our networks. Having limited mobility, I've had to rely on my online contacts at Facebook, Myspace and Twitter for my membership. Though collectively numbering in the thousands, it's still a slow process since most people are stuck on Facebook these days (that will soon change).
I'm in the process of totally reworking my network, and bringing on some folks who can help me reel in new members, and help moderate my site. Eventually I will begin having contests, and giveaways. Nothing keeps people coming back for more than free stuff. LOL
My network caters to Metal bands and fans, and I know quite a few of them. I hate asking for their help, but I'm going to start. Once they see the new look in a few weeks, I may not have to encourage them though.
Anthony's idea might be best for you. Craig's List or maybe a trade publication.
What would I do? Before I start, let me just identify myself. I do hobby internet broadcast.
If Music was street game, I would be the well known corner pusher.
You have 1000's....LITERALLY 1000's of stations on the net. SHOUTCAST, ICECAST 2, and then all the pirate stations that wouldnt need to get ASCAP/BMI/SOUND EXCHANGE.
Offer a vice. Start making friends with the hobbyist. Lots of sites where we meet. www.broadcastingworld.net, the forums of www.loudcaster.com (this is a JLA licensed group radio site, ASCAP/BMI/SE licensed broadcasters like myself. If artist are registered with SE, this is a must for making friends.) winamp forums. Hell, If A Dubstep artist approched me with music? I would throw it in rotation, get him some facetime on the air, and help to promote his events.
my site: www.thebeattransit.com
Make friends with the broadcasters, encourage them to get the unsigned artist their promoting under one roof, recommend great unsigned talent on your site to them. Hell, see if you can do a banner exchange and get some add time on the air from them. As long as money doesnt exchange hands with it, its considered a public service announcement and legal with the SESAC.
but thats just me. My little rant in this. The artist and the broadcaster are the most screwed people in this industry, and we do all the legwork.