Back-Up PS3 Saves?
Solution 1:
To back up the save from a particular game there is an easier way than backing up your entire hard drive. Just use a thumb drive in the USB slot, and go to the "Saved Data Utility (PS3)" item in the PS3 menu (it's above "Trophy Collection"). Then select a save file and press triangle, then select copy. You should see the thumb drive listed as a destination.
Solution 2:
Also, saved game backup is one of the features included w/ subscribing to PlayStation Plus
Solution 3:
Yes, you can back up your PS3 data to an external hard drive. Watch the following video to show you how to do it from the system menu.
Solution 4:
Be aware that backing up saved games to a USB thumb drive, and potentially to an external hard drive, doesn't always guarantee saving all of the associated data-- games with online components, like Rock Band, can restrict the ability of a user to backup the data associated with the saved content. I found out about Rock Band's issue the hard way...