Amazing Capitals groups can be found on a few social networks.
The Rhine Ruhr Region can be a lonely place for foreigners, especially those whose German is not up to scratch. Local culture is unique and the habit of popping down the pub before the journey home from work is not as widespread as in the UK. Posts on several websites and queries to Amazing Rhine Ruhr emphasize the difficulties.
Most have a facebook account, Linked is very popular among business people in the US as is XING in Germany.