Facebook. MySpace. Insert the name of your favorite social networking site here. These Web sites allow you to connect with contacts of all types — old college chums, family members, acquaintances, co-workers, perfect strangers — but they also largely have something else in common: advertisements. How are you supposed to promote yourself and your professional services if these social networking sites are so preoccupied with their own marketing agendas? Find out if you should be Clocked In instead.