At the current digital era with an increasing globalisation a social network is a suitable instrument to stay in contact with colleagues, former colleagues and places of acitivity. Special customised social networks for scientists fulfil the most important functions to the networking and to collaborative working. The significant difference from popular social networks like Facebook, Twitter & Co. are the unique users and the various capabilities of scientific cooperation. This contrasts strongly with the mainstream and is an essential reason to join them. Each of the 12 presented services can score at different fields. Finally it depends on the acceptance by users and on the critical mass of members, which network will become successful.