I wanted to do some offsite backups and I have about 85GB to backup. I tested out some of the popular solutions (I'm based in the UK, and of course YMMV):
Carbonite = v.slow uploads ~300kbit/s - price £3.49/month for unlimited storage*
CrashPlan = v.slow uploads ~340kbit/s - price £1.89/month for unlimited storage
SpiderOak = slow uploads ~700kbit/s - price £6.30/month for 100GB
GoDaddy = fast uploads ~5Mbit/s - price £1.59/month for 100GB
Mozy = very fast uploads ~8Mbit/s (uk server) - price £7.99/month for 125GB **
iDrive - fast uploads ~6Mbit/s - price £3.20/month for 150GB
OpenDrive - max file size is only 1GB for cheapest plan, so didn't test it.
* Note that it seemed to mysteriously slow down to 300kbit/sec only after I had exceeded 3GB of storage, before that it was much faster.
** Mozy may actually be faster than that even, as my upload connection maxes out at ~8Mbit/sec.
Prices are obviously subject to change - correct at the time of posting.
Some backup solutions have versioning - but that will just use up your storage space, and you should be doing that with your local backup solution, not your offsite solution.
I found that some of the software was exaggerating/misreporting its real upload speed. So I had to use a "desktop gadget" called Network Meter to monitor activity.
Unsurprisingly, I've gone with GoDaddy for now due to the solid upload speed/price combination. (No I haven't - see update at the bottom!) The downside is that it's not quite as quick as Mozy, and the backup software is very basic.
Generally I have noticed that when it comes to online storage of any kind (backups/photos/ftp/web/email) - the web hosting companies are always some of the cheapest.
Now if I could just find a UK webhost that was cheaper than GoDaddy and and had a better software client. There's always room for improvement.
I should say though, that despite the GoDaddy client being very basic, it puts hardly any stress on the system while I am using it, which is worth a lot to me. The other clients tend to do advanced file-diff comparisons to "save you space" which stress your CPU. In reality, a simple modified date/time check is all most users need, and its not really to save you space as much as save them bandwidth by only uploading file differences at the byte level (or some such). Your CPU time costs nothing to them, but you have to pay the power bill for it. So all round, I'm quite liking the GoDaddy solution atm, but it's early days.
What's interesting about the Mozy client is that it seems to detect if a file you are uploading already exists on their servers in someone else's backup, and if so, it doesn't upload your file, but just creates a reference. This is clever, but... it still counts against your usage allowance!! Cheeky.
UPDATE: since I wrote this, I have discovered that the maximum file upload size for GoDaddy online storage is 1GB (despite the fact that it says file size is Unlimited on their product page!). Some of my files are bigger than that, so I've switched to iDrive, and I've got to say I'm pretty happy with it. I upload several gigs/day to iDrive with no problems.