Went for Jungledisk... the reasons? Pretty good.
- Excellent storage / cost per GB extra (no up/down charges like amazon s3)
- Rackspace product - Support is fantastic, any issues resolved in minutes in real time
- JungleDisk supports servers and workstations (in x86 and x64 and linux GUI/Power users)
Only other alternative that I'm aware of, is Acronis Backup and Recovery server edition (£800 ish for server license + additional for clients). I need a centralised solution pulling from multiple clients.
$5 per month for server (10GB included and additional GB @ $0.15 automatically billed)
$4 per workstation client
Pretty happy so far, pushed my 17GB update yesterday with no issues.