Need Example of multiuser contact manager

[ck01]

I've got a contact manager application that will be split and the backend will run on a server. I would like to take it to the next step where users can download their current appointments and upload any changes. It would be nice if they could do all of this from the field by logging into our Microsoft Server. However, it would be acceptable if they had to be in the office to do this. This is new territory for me and I would greatly appreciate any feedback, help and espcially an example.

Thanks in advance!