MXR's M239 Mini Iso-Brick is a power supply that provides DC power to several different pedals. You get four 9V 300mA plugs on the side of the Mini Iso-Brick, in addition to two more plugs for 9v @ 800mA and 18V @ 800mA. Plus, it takes up an incredibly small amount of space, and has green LEDs so you can easily identify a good output power connection. The Mini Iso-Brick is a conveniently-sized power supply with range of options so you can power your pedals without hassle.

Specs:

Input 18V: At 2 Amps regulated supply (positive barrel negative center 5.5mm x 2.1mm plug)
Outputs: 9-18V @ 800mA (switched)
(4) 9V @ 300 mA
(all positive barrel negative center 5.5mm x 2.1mm)