Find Current Working Websites Linux

i have had a dedicated server fro two years now. you're service has been so reliable that i have not done any administration to my server for two years. this year one of the websites on the server has grown tremendously and we need to migrate that website to another dedicated server to handle the content, however, there are also other websites we have running there and i dont want to touch those, can you show me how to find current working website names in linux. is there a command i can do in the shell so i can find this information as to how many domains i have in my current server?