One occasional frustration of life with a refillable water bottle is not knowing where you can refill it. If you're out in the city it can be a lot easier to just cave and buy a bottle of water than wander around looking for a drinking fountain.So kudos to TapIt. Their site and iPhone app will help you locate friendly cafes where you can fill up your bottle for free. TapIt is only operating New York at the moment, but the service would be useful in any metropolitan area. Hopefully they'll branch out soon.