Smalltalk on Java VM
Check this out. Another Smalltalk running on the JVM (Of course, I only knew of one other, but I had never heard of this one). It's called Talks2. The site is in German, but the Talks2 stuff is in english.
Now, did I mention that it has a full class browser, transcript, and DEBUGGER?! Wait, if that's not enough, you also get become: and full Smalltalk exceptions! How cool is that?! It's a minimal system and they are some rough edges, but DAMN, I am impressed! Great work guys and did I mention the liberal license? They also compile to Java code (not byte codes) and you can see how they implement things. Very cool. I would love to write code that compiled down to JBM byte codes. It would be a fun project, don't you think?
Anyway, chalk it up as another Smalltalk version! Weird thing is that I was looking for RETE algorithms in Smalltalk and ran into this by accident. COOL! Are you still reading this? GO NOW!