When you and I are ready, no longer earthly-bound
We'll travel through the crystal night, Starbound
 – J.J. Cale
Second in the Travelin' Light series
I try to be ready for anything on the road, a tendency that was burned in during my scout leader years of "Being Prepared." I have a habit of traveling with a nice big stack of crisp maps and guide books. This does not work well at all on a bike, or really on any trip where you want to keep the load light.
Apps on my iPhone screen: Google Drive, MapMyRide, Pinterest, Kindle, Yelp
Smartphones are changing that, with apps that put the data in your hip pocket. The limiters are battery life and cell service, but there are ways to mitigate those limiters, like doing your research ahead and using apps that allow you to store the info on your phone so it doesn't have to download the data from the Internet every time.
Here are my top 5 go-to apps for a road trip.
Drive DetailsGoogle Drive
1. Google Drive
Drive makes it really easy for my husband and I to share the trip research we do on our desktops. I set up a folder for the trip on my Drive account, share the folder with him, and we can both drop in PDF maps, brochures, schedules on spreadhseets, notes, you name it.
You can make files available in the Google Drive phone app even if there's no cell service. To do that, tap the little 'i' by the filename, and set the "Available Offline" choice at the bottom to ON.

MapMyRide App screen

2. MapMyRide

I have yet to find the perfect mobile map for my purposes, but this one serves. MapMyRide uses your phone's GPS. The full site has a great toolset for creating routes on my desktop that I can open in the app. You can share routes with friends and find maps other people have saved nearby. Now if they added voice navigation we would really be cookin'.

3. Kindle

If you can find your travel book of choice as an eBook, Kindle makes it available without cell service. This guide on the Pacific Coast route has great directions, maps, points of interest and helpful bits like where to find grocery stores along the way.

4. Pinterest

I don't rely on Pinterest for any mission-critical data since it requires cell service, but its fun eye candy for planning stops along the way. Its also easy to set up sharing so that other people you designate can pin things to the same boards.
Yelp screen

5. Yelp!
Like Pinterest, you need service to use Yelp. It finds nearby restaurants, stores and business and serves up helpful information like hours, menus, directions, contact information and reviews from other visitors.
The Bookmark feature is handy if you want to check out places to eat ahead of time and quickly pull up your top choices, or mark favorites you or friends have been to. Just be aware that not all reviews are legit. As Ken Charvoz explains in his article on online rating sites, Yelp has been taking a hit for fraudulent reviews.
As I mentioned at the start, battery life can be a concern, especially if you are watching your progress on a mapping site. It helps to close out apps you are not using and turn off Wifi and Bluetooth if you are not using those. Having a way to recharge enroute is pretty helpful too. My husband is the real MacGuyver on the team and has set up a mobile solar charger on his bike rack for backup power.
What are your favorite apps for traveling?