Smalltalk YX is a Smalltalk-80 implementation. It's highly portable, and runs equally well on 32-bit and 64-bit systems, Mac, Unix, Windows, WinCE, or Solaris. It has an easy-to-use plugin system and is very active.
At one point, Open Hub analyzed source code for this project based on code location(s) available at that time. Since then, the code locations have been removed.