I've never really looked much into Lua before? Does it also have some sort of unifying base underneath it all? I liked Why's Potion because it reused many of the same syntax constructs in different places, so that there were few special cases.
It does, actually. Lua uses tables as its underlying data structure in the same way that Lisp uses the list. This is where a lot of its power and simplicity comes from. In fact, the language authors have stated how Lisp was one of their inspirations for the language.
Lua is intentionally very small ("doing more with less"). It has a lot in common with Python, Scheme, and Javascript, but was designed for embedding, and where Python prioritizes "batteries included", it puts more emphasis on "small/simple/powerful". (If you're extending a C project, you've already got libraries.)
The _Programming in Lua_ book is the best place to start. The previous version is free at http://www.lua.org and will give you a good impression. (The main diff between 5.0 and 5.1 is the module system.)
