A few enterprising young folks, including (full disclosure) a graduate student at Brown CS, have created a map mashup to track the US election candidates, Map the Candidates. The time-travel feature is quite interesting, and will become more so as the primaries approach.
The site has much more potential. Every press pundit takes pride in predicting who will become a candidate one or two years hence (of course, we only remember their hits, not their misses). By tracking news articles a site like this could perform similar forecasts, and take the bloviators largely out of the mix.