Habitual Foursquare users don't have much context for their check-ins -- it's easy for them to track their favorite haunts, but not their long-term trends. The just-launched Foursquare Time Machine could help draw those missing connections, however. Sign in and it creates a map-based timeline of each and every check-in, color-coded by its nature. While the superficial result is a very pretty light cluster, it's surprisingly functio
