Coffee shops and rest stops have become de facto charging stations. Depending on how many devices you like to bring along with you, you may wish to invest in an all-in-one quick charger to top up your batteries when you stop somewhere with available electrical supply. At our most-techy, we typically pack two tablet computers, at least one cellphone, two helmet-mount Bluetooth communicators, and a digital camera. Add four battery packs for charging all of that when we’re away from the grid, and our rig can amount to over ten devices, any (or all) of which could use a little electricity to keep them going at any given time. (OK, we might let the tablets or our camera go without electrons, but our helmet communicators are an essential tool we just don’t want to ride without).
Juggling separate chargers for each device we brought became very inconvenient (and, depending on outlet availability, sometimes impossible), so we now have a six-port high-speed charger (sorry, no link).

Six ports is usually enough; we may carry a couple of extra USB plug-ins (the kind with two ports each) just out of an abundance of caution, and to share with fellow travelers as needed.
I favor little 3″ USB cables for charging from this thing: they’re easy to pack and to manage, and it keeps the whole charging-station thing from becoming an unmanageable spaghetti-sprawl when you’ve got a bunch of devices charging up.
Before we got this six-at-a-time rapid charger and the tiny USB cables, we had a travel-size USB hub, which we’d plug into a bricky plug-in, which itself plugged into whatever electrical outlet we could find. To accommodate more than the four devices the hub could charge, we brought along a smallish power bar and a bunch more USB plug-in bricks.
Here’s a picture of our old setup looking extra- tidy at home, before a trip:

The bag in this picture is a Pacsafe Metrosafe waist pack. This little belly-bag is an awesome bit of gear that lets you lock your charging devices in a steel cage (yup, Pacsafe = both a pack and a safe!) and then lock that cage to an immovable object. The top of the pack has a little pass-through designed for headphone cables, which we run the main electrical cable through.
Here’s a picture of our charging setup all spread out (not yet secured in the Pacsafe) at a campground in Idaho:

The Pacsafe bag lets us set our devices to charging, and then walk away! When we can find an inconspicuous place to lock-and-charge like this, we sometimes even leave our devices charging overnight.
A couple of years back we bought our four Ocho brand portable power supplies. These little guys have kept our devices going even when we’ve had several days out in the wild and away from the power grid. They’re tough enough to survive our motorcycle-hammock-camping lifestyle, and each one can fully charge one of our tablets or do four or more charges to one of our helmet communicators. There are smaller power supplies out there, but the price was right on the Ochos and we’re pretty happy with them.
NMBL