R1soft (for servers) – widely used, can restore data in a few clicks

Siteautobackup.com (associated with Hostgator) – for Cpanel/WHM accounts
Base 1,000 MB Backup Account
•Backup Unlimited Websites, Domains, Emails, Databases
•Backup Unlimited cPanel Accounts
•Backup Unlimited WHM Accounts
•Only $1 per additional 1,000 MB
$1.95 USD Monthly
$19.50 USD Annually
Base 5,000 MB Backup Account
•Backup Unlimited Websites, Domains, Emails, Databases
•Backup Unlimited cPanel Accounts
•Backup Unlimited WHM Accounts
•Only $1 per additional 1,000 MB
$4.95 USD Monthly
$49.50 USD Annually

http://www.bacula.org/en/

http://www.bqinternet.com/backup/

Packages:
•10GB – $5/month
•100GB – $20/month
•2TB – $150/month
•Custom size
Features:
•Daily backup using Rsync technology
•RAID6 storage
•SSH encryption
•On-the-fly compression
•Get back online instantly with a Samba mount
•FTP access
•No data transfer limit
•No setup fee
Resellers include Rsyncpalace

Other options
Ahsay
Vembu
CrashPlan Pro
Kaseya
Asigra
Novastor
BackupExec
Genesoft
zmanda.com
Amazon Simple Storage System (S3)