Tcl Code

A fantastic scripting language, Tcl is just about the most dynamic thing out there. Tcl has many great features and does a lot of things right:

Lots of useful features builtin to the base (though not so much that it becomes bloated; compilation from source takes less than five minutes).
Does exactly the right thing for many commands (e.g. file manipulation, sockets, etc.) no matter what platform you're on — write truly portable code with no hassle.
Highly dynamic nature allows great flexibility to write functionality that looks builtin; commands choose how to evaluate their arguments so writing new control structures is quite easy.
Wonderful cross-platform graphical toolkit is tightly integrated, so it's easy to make a GUI for your program if it comes down to that.
Highly useful libraries that cover just about everything you'd ever need, including the very portable Tcllib which is pure Tcl code.
Last but definitely not least, an excellent community that's both friendly and helpful.

tcvJSON

This started out as a library to encode JSON (as opposed to Tcllib's json package which only does decoding) but it's becoming more.