USB Flash Drives for Backup/Long-Term Storage?

cyberdigm is curious about this issue: "I am writing two books and have just recently gone through the trauma of having my hard drive flake out (physical damage to several sectors). Fortunately, while the OS instance was trashed, the file system is still intact, so I have been able to recover my files.Given that, I am now much more aware of the needed to regularly back up my files. I'd be interested in any opinions about the suitability of USB flash drives to help me solve this problem. The idea would be to store copies of all my files on a USB drive and back them up every day. I like that USB drives are generally fairly cheap. My concern is the long-term wisdom of this approach. Are there (practical) rewrite limits for USB flash drives? Is there a chance that the data would degrade on the drive over time? Other alternatives I am considering include external/USB hard drives. Of course, an overarching concern is that I'd rather not spend a lot of money."