I have books #1 and #3 and they're both excellent. As for #5, it's worth pointing out that the entire wiki is full of good stuff, not just the tutorials, once you've got your footing.
At least one of the recent Game Programming Gems books had a Lua article, though that might be a bit pricey if you don't care about the rest of the content.
I borrowed
Game Scripting Mastery from a friend back when I was learning Lua and thought it gave me a pretty good summary (and comparison versus Python and Ruby), though it's 5.0 and I don't have it myself to judge if it's aged well.
Haven't read it and never play the game, but throwing it out there:
World of Warcraft Programming
beatthelastboss wrote:I will add things to this list as more people post things are must-haves for lua users--I am talking books, videos, websites, memberships, magazines, anything that could help someone get started.
As far as videos go, you might look up "Lua Workshop" on YouTube, or dig around for that in the mailing list archives. A lot of that is fairly special interest, though.
Following the WoW book mention, I can think of a couple APIs to inspect off-hand:
World of Warcraft
Warhammer Online
A couple relevant things from the Lua community:
Lua Nova
Snippets
And for memberships, the mailing list:
lua-l
Lots of good stuff in its archives, too.
For understanding the Lua implementation:
Reading order
One of the best ways to become proficient is to read useful code written by others, so a few sites for that:
LuaForge
Kepler
LuaJIT
MetaLua,
blog
Also, echoing Robin, it's good to get your feet wet with some other languages. I tried to find some decent tutorials and books while getting my coworkers up to speed on Lua, but a lot of what I saw was "Hey, look how I can write C or C++ code in Lua"-type stuff, and nothing worthwhile on, say, major features like closures, coroutines, and weak tables.
Imperative and OO code are of course fine and useful in themselves; but using just those to the exclusion of the functional paradigm is silly and limiting. Some books and sites I've found either helpful or enlightening here:
Lisp and Scheme:
ANSI Common Lisp
On Lisp (This is kind of heavy, but if you follow the general ideas you'll see some of Metalua's motivation.)
Practical Common Lisp
SICP
Erlang:
Programming Erlang
Haskell:
Learn You a Haskell for Great Good! (Maybe it's just me, but I found this one a fun read in light of Mike's tutorials.
)
ML:
Purely Functional Data Structures (A nice supplement to one of the Lua Gems.)
Anyhow, this was probably a lot to throw at you, but I've found it all helpful to have read or at least be generally aware of, as a Lua programmer.
) The problem is, I am not very experienced in it, and only understand the very basics... So, my birthday is coming up soon, I would LOVE (No pun intended) to see what you guys think every lua user should own if they have money or friends to get them things 
)
)
