Here is an awesome web app to visualize your foursquare check-ins, login with foursquare and Weeplaces will show your movement on a map over time. At the end of the visualization you will be left with a map with all your check-ins. You can then share this visualization with friends using twitter/facebook.
However one thing I noticed was that once you login and use this app, your check-in data is all made public even if you don’t want to share this information, anyone can access this data by using this url www.weeplaces.com/(firstname)-(lastname), there was no option to make this url private again. I have contacted the guys from Weeplaces regarding this privacy concern.
Update: I got response back from Weeplaces, a privacy setting option has been added to make the visualization private.