My List.
Consistently All easily accessible in China
Hefeiexpat - My main source of connections both social and business.
HefeiConnect - If you are living here, you need this one.
WeChat - Handy tool for maintaining contact.
Linked in - Good for business and career contacts.
Skype - Video link, voice and text.
Occasionally Requires VPN service
Facebook - I maintain a presence.
Rarely
Yahoo Messenger - was a great program in its day but still has uses.
Never
Twitter - I never really used Twitter, I have hefeiexpat.com
MSN - I never liked nor trusted MSN, it was a favourite for hackers, I used yahoo messenger.
QQ - To open and to easy to get hassled.
I rarely use social networks I can't easily access in China.