Don't mean to hijack, but could I be referred to a good introduction to Lua? I keep hearing about it, but it's one of the few languages I know NOTHING about, and I have a free weekend!
Like K&R, it's style is colloquially terse, yet each sentence is chock full of information. It's a great book for someone who's already coming from another language like Python.
If you're into graphics programming, then http://love2d.org/ would be the perfect vehicle for you to get into Lua while you read PIL.
There's an older edition available for free online[2].
Then there's of course the lua users wiki and its "Learning Lua" section[3].
I find the wiki a little hard to navigate so I just went ahead and bought the book. IMHO the gems in Chapter 10 (Complete Examples) and the clear explanation of coroutines are alone worth the price. The rest is a very nice bonus too.
[1] http://store.feistyduck.com/products/programming-in-lua [2] http://www.lua.org/pil/ [3] http://lua-users.org/wiki/LearningLua