Foursquare-history-map is a project mainly written in Ruby, it's free.
View all of the venues you've checked in on a map. Example:
View all of the venues you've checked in on a map.
See an example here: http://nakajima.github.com/foursquare-history-map
Run the history grabber:
$ ruby history.rb
It will ask for your Foursquare credentials, then grab all your checkins.
The checkins will be saved in history.json. Feel free to play with your data.
Start the server:
$ ruby app.rb
Open http://localhost:4567 in your browser for a friggin sweet Google map.
(c) Copyright 2010 Pat Nakajima. All Rights Reserved.