localchan is a Google Maps mashup that lets you follow threads on the 4chan bulletin board directly from a map.
Discussion threads are displayed on the map with heart shaped map markers. If you click on a map marker the thread loads in a window overlaid on the map. The locations of 4chan users who have replied to the thread are shown on the map and a line connects each of the markers to show the chronology of the discussion.
If you click any of the user names in the discussion thread window the map will centre on that user's location. It is even possible to join in any of the 4Chan discussion threads by clicking on the 'reply' button.