AvePoint: for SharePoint farm and more granular backup and recovery for MOSS 2007 and WSS 3.0. The tool is called DocAve 4.1.
Commvault: for SharePoint Farm backup and granular recovery although its not clear from a cursoryuu browse of their site if it’s possible to recover on a site by site basis.
Neverfail: for high availability and Disaster Recovery solutions. Includes MOSS monitoring capability as well.
Quest: Compressed database backup with Litespeed and Recovery Manager for SPS 2003 and MOSS 2007.
If you want to read more about this issue Joel Oleson has a excellent blog entry on this and other disaster recovery scenarios.
Update: I’ve recently become aware that Idera also have a good product in this space too…