location views ip anonymous users

I have a website that has a large amount of nodes with locations and ratings associated with them. When an anonymous user visits my site, i need for it to determine the city of the user and display to the user the highest rated node within a set distance of them.

Also, it would be an added bonus if I were able to display a map which was centered on the location of the anonymous user.

If the user were to be logged in, I would like to use the location specified at profile creation, but getting it to run off of the ip address determination first is most important.