On Where's Tim, you can now see where I was on a specific date.
Entering a date in this box:

will get you this:
Clear History = Removes the history overlay
Export History to XML = Generates an XML document with the lat/long data
Disable Auto Update = Temporarily disables the Auto Update feature so you can move the map around and browse my previous locations without the map recentering itself
Note that the history function doesn't work that great in Firefox. And that getting dates with a lot of data (like 01/01/06) will take 30 seconds or more to populate the data and display it on the map.
The data has also been added to the Where's Tim Webservice.
Calling the GetTimsHistory function will return an array of a GPSData structure.