I've been a big fan of VMware for the last year or so. I've mentioned previously that I use it to run EDA tools on my Windows based laptop. Today I was browsing through some of the free virtual machines that can be downloaded and run on the free VMware Player and noticed that a company called ALM Works Ltd. has released a free virtual machine that runs Bugzilla! What's the catch? Well, the virtual machine is a stripped down version of Linux - so stripped down in fact that it doesn't have gcc or make installed. That made it impossible for me to try to upgrade to the latest release candidate of Bugzilla (since the MIME::Parser package is missing from the Perl installation which requires make to build). It seems the main reason for ALM Works to release the VM is to push their Deskzilla desktop interface to Bugzilla. Not that there's anything wrong with that... :-).
A TWiki VM is also available. I'd highly recommend checking out the entire list of VMs - it's much easier playing with them in the player than attempting to build up a new system each time you want to try something new.