Big fan, but only recently have I used them. Two reasons:
Gives me a VM where I can do crazy things like editing the swap file, rebinding port 8080 to 80. All without breaking stuff. Even with such control, if I do bad things like DNS queries, someone can spot it. I have all the safety, total isolation, and still someone catches my mistakes. If it all goes wrong, we'll just format it.
I used VirtualBox to set up a Ubuntu workspace. I used: