When we need to choose a good electrician, plumber, hairdresser or mechanic it is often very important for us to have a recommendation of our good friend. Also, almost each of us has such "useful" contacts in the address book of a smartphone. Handshaker is an excellent mobile application that helps you to see what useful contacts have your friends and share your useful contacts with them. It also allows you to post ads for a close circle of friends. When you post ad in the app, it will be only visible for people, who have your contact in their address book. Then they will be able to repost it to their friends and further. So, when you post ad in application, it will be first seen by your friends, then by friends of friends etc.