Mapping sales staff ? Does Google Work?

[Golfman]

I would like to create an online map that all our staff can share so we can geographically “push pin” where our sales reps go to across the UK, to help us avoid missing out areas, and helping when a customer phones up and says “who covers my area”? Also we should be able to add distributor areas so we can avoid overlaps etc.
Does anyone use something like this, or know hoe I can set something similar up?
Thanks.