I'm a big fan of vmware and run the majority of my development and test environments off of two physical machines with lots of memory and disk space. I usually create what I call base images of say Ubuntu or Fedora with all the updates and then make copies of the virtual machines for specific uses. This approach has been great but I've still got to the actual work of taking a base image and making say a subversion server.... Till now.
vmare has introduced the Virtual Appliance Marketplace where you can now find specifically configured machines all ready for download! Want a Fedora 8 image? One is available. Want a small Linux image? Try the "Damn Small Linux Virtual Machine". Want a machine that is specifically configured as a subversion server? They have one of those too. I might even give Sun Solaris 10 a spin (I've never been able to configure Solaris in vmware right but now that I don't have too...) The machines run in vmware workstation, player and server.
To the geeks that like setting up operating systems, I salute you!
-Charles Angione