the coffee houses are a good place to meet people as there is often live music or performances (crossroads on ridge ave) or art exhibits and a bike culture (la colombe or mugshots on main street)

also, the manayunk sport and social is a great way to join a local volleyball, kickball, softball or football team...all coed and recreational...they have a ton of events and I have made quite a few friends from my participation

the phillyblog meetups are cool......get a dog, their is an entire dog subculture here (as is cycling and music)