I've experimented a lot with Google map mashups over the last few years (e.g. www.classicmotormap.com).
Spiggler was one such experiment which searched Twitter for tweets with geolocation data attached to them and plotted those tweets on a map.
It was particularly interesting to view tweets around a particular event (Le Mans, GPs etc) as you'd see team members tweeting info from the pits. Since closing it down I've also found out that it was used by the police in the USA to find witnesses to a number of crimes.
So sadly, Spiggler is no more.