If you've ever tried to power more than a couple of effects pedals with 9 volt batteries, you know how frustrating (not to mention expensive) it can be. At first, may guitarists and bassists will graduate to using dedicated power supplies, which definitely saves money but can be messy and expensive. What's the best solution? Easy. A dedicated pedalboard power supply.
Pedalboard power supplies are capable of powering multiple effects pedals, even those with different operating voltages (e.g. 9V, 12V, 18V). Generally, two types are available - Switching and Individual Output. Switching power supplies (such as the Visual Sound 1-Spot) use a single transformer that steps up the voltage as needed, connecting all effects with a daisy chain. Such power supplies, if done right, are inexpensive and highly portable. Some pedals, though, don't play well with switching power supplies.
Perhaps the most robust (and expensive) solution is a power supply with individual outputs, such as a Voodoo Lab Pedal Power 2. This unit will not only power several pedals, but will power pedals with different voltage requirements.