Facebook is no longer a good place to find friends - people only want to connect with those they already know in real life.
Myspace is run over with spam and musicians, so yes, I agree penpal sites are a great place to meet friends, or smaller social networks. Most of the big networks are just too "high profile" to meet nice friends locally, or even non-local.
Orkut and Friendster are big but still kinda down to earth.
Otherwise would recommend joining some interest based discussion forums.
As far as penpal sites, I've used Penpal-Net or something like that, and also [url]www.JuJu.cc[/url] which is a baby site.
If this helps, let me know, and I can research further small networks. I do think forums are one of the best things though, even after all these years
P.s. my first, post, what's up all, I'm checking out towns in Colorado on city-data...