Crashplan, here's why:
*unlimited space
*web restore, iphone restore, built in app restore.
* seeding (you send a drive with your files) and restore to your door ( they send a drive with the files)
* data de duplication and compression
* Live monitoring ( doesn't scan the entire drive for changes )
* they allow you change file versioning to your needs ( even every min)
* Backup sets -> different settings for different folders, say you need more versioning for your docs than your pics.
* Backups to external drives & friends house (free)
* low cpu usage ( although it is a java app) , it runs constantly but is easier on the battery than running entire scans every hour.
* allows you to set cpu usage
* they never delete files by default , backblaze does if you don't connect your externals every 30 days.
* 448 blowfish encryption with user set key
a bit slower than other alternatives, like backblaze for example, however i didn't feel like their app was customizable enough and really didn't like the 30 day file deletion. Also hourly entire drive scans consume battery.
they have a free 30 day trial and a really impressive client list (nasa? google? adobe? evernote etc)
I've just subscribed to Crashplan, you can chose what folder you want to upload and keep updated.
It defaults to your Home folder on a Mac, but you can chose any folder, so just make a folder on your HDD and use that?
There you go
for the price it's hard to beat.