Crashplan is having a promotion to get people who are unhappy about the recent plan changes to Mozy (another online backup service). As such they are having a 15% off discount for Mozy users. However if you go to the webpage it gives you the discount without any mention of Mozy or whatever.
I was using the trial version and I went thru the whole process to get a 2 yr subscription with the discount easily so it seems to be available to anyone.
Link to discount: http://www.crashplan.com/mozyonover
Crashplan is great. Have the free version installed to backup my home pc to my work pc. You could do the same with a friend's computer and be each other's backups.