Here is a number of software and services that I have had success with in the past,
Hosting – http://inetu.com , http://rackspace.com , http://rackforce.com , http://mediatemple.net
Backup – http://www.bacula.org
Monitoring – Nagios , WebSitePluse
Configuration – http://www.parallels.com/plesk/ Plesk
Virtualization – http://vmware.com and http://xen.org
Testing – WebTest http://webtest.canoo.com