Apple makes a USB power adapter:
http://store.apple.com/1-800-MY-APPLE/WebObjects/AppleStore.woa/wo/2.RSLID?mco=63413C01&nplm=M9837LL%2FA
which used to come standard with iPods but is now an extra cost accessory.
An alternative is a cheap powered USB hub like this:
http://www.newegg.com/Product/Product.asp?Item=N82E16817392006
which will supply power to any device connected to it. Not as elegant as the Apple product, but cheaper and more practical.
http://store.apple.com/1-800-MY-APPLE/WebObjects/AppleStore.woa/wo/2.RSLID?mco=63413C01&nplm=M9837LL%2FA
which used to come standard with iPods but is now an extra cost accessory.
An alternative is a cheap powered USB hub like this:
http://www.newegg.com/Product/Product.asp?Item=N82E16817392006
which will supply power to any device connected to it. Not as elegant as the Apple product, but cheaper and more practical.