Packing List for Android (free) and iPhone’s Pack & Go ($1) allow you and your co-travelers to create, share, and collaborate on completing checklists for everything that needs to be packed or accomplished before you hit the highways.
Telenav is a navigating service that can eliminate the need for a GPS unit. Even the free version improves on smartphone services by offering one-touch rerouting. (Android and iPhone)
MAD Maps gives directions, plus a little local flavor, highlighting scenic routes, worthy detours, and local trivia. ($1, iOS only; Android version coming soon).
Sit or Squat, a free app from Charmin, locates the restroom nearest to you—for those times when nature calls and “it seems like the only thing around is, well, nature.” (iOS and Android)
Source: Good Housekeeping