Did you know that you can use a $20 USB hub (but not just any old USB hub) to power a Raspberry Pi AND use the SAME hub to add additional USB ports to the Pi? Well, you can, as demonstrated in this video:
Apparently not all USB hubs will work, because many only put out something close to the 500 mA that is the specification for USB 2.0, whereas the Raspberry Pi Model B requires 700 mA. So, the hub has to put out a bit of extra current or it won’t power the Raspberry Pi properly.
There is a list of USB hubs that will work with the Raspberry Pi, but pay special attention to the comments in the rightmost column. Only a few of the USB hubs shown are known to be able to power the Raspberry Pi reliably. The one shown in the video is the Plugable 7 Port High Speed USB Hub, model USB2-HUB-AG7 (Amazon affiliate link – we make a small commission if you click on it and purchase a unit).
EDIT: A few weeks after we originally posted this article, the device described in the following article was released:
PiHub from Cyntech and Pimoroni – a new powered USB Hub for the Raspberry Pi
Unless you really don’t need that many USB ports, and you absolutely fall in love with the Raspberry-shaped case of the PiHub, we suggest you stick with the Plugable 7 Port hub mentioned above. Not only are you getting more USB ports, and a hefty 3 Amp power supply, but if you’re in the U.S.A. or Canada it’s actually available here and has mostly 4 and 5 star reviews on Amazon. And if you go with the PiHub, by the time you do the currency conversion (and let your credit card company take a small bite on the exchange rate), and pay for the shipping, you’ll be paying more and getting less (only four ports rather than the seven offered in the Plugable unit). But, you will be getting that lovely Raspberry-shaped case, so there’s that.