Amazon has released an off-site backup program called S3, for Simple Storage Service. It is aimed primarily at developers, letting you store up to 100Gb in files for $15 per month, with bandwidth charged at 20 cents per Gb transferred.
The only access to file storage and retrieval is through their API, but the pricing is much lower than most webhosting backup plans. Amazon offers toolkits in several development languages to get you started. I just might start using this for cheap offsite weekly database backups of my web apps. Matt Haughey