Parrot is a virtual machine that provides the base for Rakudo and a large number of other languages. I honestly can’t tell you what its virtues are compared to other virtual machines, because I’m just not that well informed.
I have been exploring PIR, the Parrot Intermediate Representation language. It’s a lot more low level than what I’m used to, but it is still a lot of fun to play with. You can follow along, if you like.