The best backup is multiple copies, in different places. I would keep your copy on the computer or an external drive, plus put them online.
Specifically for photos, I like Google’s Picasa for sorting/filing, and Picasaweb for online storage.
2GB free, 20GB for $5/year
https://www.google.com/accounts/PurchaseStorage
For all types of file storage, here are the options I’ve looked at:
1)
Microsoft’s SkyDrive 25GB free
Drag and drop works with Microsoft Internet Explorer
Other browsers use the normal file browser (like the ‘Open’ dialog in most any program)
http://skydrive.live.com/
SkyDrive Explorer puts a friendlier desktop client on SkyDrive
WIndows only
http://www.skydriveexplorer.com/
2)
Microsoft Live Mesh offers 5GB free and a drag and drop desktop client.
Windows, Mac and Windows Mobile versions
https://www.mesh.com
3)
Dropbox.com is really great, highly recommended by me. You pick a folder on your PC, it keeps the folder backed up to the cloud AND any other computer where you install Dropbox.
You can also upload & download from a web browser, so you can manage your files from any Internet-connected computer.
4)
Lifehacker.com recently had a reader poll, Five Best Online Backup Tools
It should really be called “Readers’ Five Favorite Online Backup Tools
Dropbox (Windows/Mac/Linux, Basic [2GB] Free, Pro [50GB] $9.99 per month)
CrashPlan (Windows/Mac/Linux/Open Solaris, Basic [No online storage] Free, Premium [Unlimited online storage] $4.50 per month)
Mozy (Windows/Mac, Basic [2GB] Free, Home Premium [Unlimited] $4.95 per month)
Jungle Disk (Windows/Mac/Linux, Pricing: $2 per month + Per GB Fees)
Carbonite (Windows/Mac, Unlimited Storage $4.58 per month)