I need a map program that would allow me to look at a map and put color overlays over certain streets or areas?

I need a map program that would allow me to look at a map and put color overlays over certain streets or areas and have them at 50% opacity so i can still see the streets/houses under them. It also needs to be able to have an unlimited amount of addresses put into it where the clients live. It needs to be able to have a search option to type in a clients name and have it pop up with their address and zoom in on it. I need this program to be able to be logged on by about ten different employees who can all see these overlays and data. If someone can point me in the right direction for something like this it will be GREATLY appreciated. Money is not an issue.