Has anyone set up prepaid service on a Motorola Droid (or Milestone) in the US? I'm looking for feedback and recommendations. I love the phone and Android 2.0, Google Voice integration, Dolphin browser, etc. I am not currently locked in to any carrier. I'm just looking for the best prepaid voice & data plan that will support all features of the Droid, including turn-by-turn navigation. (BTW, is cellular data always required for the GPS to work well, or will the GPS get a fix quickly even where there is no internet connection at all?) I only need cellular voice and 3g data a few days a month. I don't want to pay for a normal monthly contract. But I want all features of the phone to work when I need them. Any recommendations?