Another variation of manhunt is made possible by the wonders of modern technology. Split up into several teams, as before, but make sure that each team has a cell phone. Also, unless you're lucky enough to live in a sprawl-free city with good public transportation, make sure that someone in each team has a car and can drive. Exchange phone numbers, decide on some basic boundaries (unless you want the game to turn into a road trip), and then send out the hiding team -- the other two teams should find some way to occupy themselves for whatever time period y'all decide on. After the first ten minutes (or however long) are up, the hiding team calls each of the searching teams, and gives them a suitably cryptic clue to their location. The hiding team doesn't actually have to be in their location yet, but they have to know where they will eventually be. Both searching teams head out in their cars, trying to find the hiding team, and every ten minutes (or however long), the hiding team calls with another clue. The first team to find the people hiding, obviously, wins.
You might agree on a certain interval of time after which the people hiding win by default, but winning isn't terribly important in this game. Another variation, which is a lot more fun for the people hiding, is to have them chalk a trail of clues across the city. In this case, the hiding team would have to have a bit more of a head start.