+1 on the cloud storage. Encrypt your sensitive documents and put them on USB key as well for instant access. Chances are you won't need your mp3 collection or pictures from 2004 on short notice during an emergency.

By the time you add up the cost of NAS, Drives, setup time, checking on it time, upgrading it time, etc. then the cloud is cheaper (assuming your time is worth something). Also having access anywhere, anytime from any device is worth a lot! When you're in the hospital after you've been mugged, have lost your wallet and 75-item keychain and are asked for your insurance info you can answer "Sure, can I use your computer or smartphone?"