Another interesting interpreter is the .NET Microframework, it is rather out of date now, but it is a fascinating project. You can get a full .NET stack up and running in just tens of kilobytes of memory.
How it does types is interesting, and the GC is simple enough that it can be comprehended by mere mortals. I enjoyed my time playing around with it.
As a bonus, .NET MF is designed for production, and indeed it is used out in the wild!