GetIn2China - I study Mandarin here. Their teachers and prices are great and they also offer internship placement opportunities and visa extension services. Plus its right by my house!
Moishe House - This is the official page for our semi-official Jewish community. There are branches throughout the world. We also attend Kehillat Beijing
Beijing Ultimate organizes a summer league that I've participated in for two summers now. There are a handful of club level teams and pick up games around the city on a fairly regular basis. There is also a related blog.