Following in the footsteps of MyGuestMap, Gvisit arrives with a few new interesting features. GVisit is a tool to track visits to websites and blogs and the free version includes city and ip address of your visitor. With a small donation to the effort GVisit will display the last 100 visits instead of the default of 20 as well as removing the donation and ad links that appear on your map page. Here is an example.
If GVisit is too simplified for you, MyGuestMap might provide more admin functionality with a ton of extra customization. For quick setup and no email address requirement GVisit is the way to go..