Lua

First Steps in Programming in Lua
Short presentation on the language, examples with source code and output; syntax diagram available as PDF. English, Deutsch.
http://lua.lickert.net/index_en.html

Lua: An Extensible Extension Language
Overview from journal, by Roberto Ierusalimschy, Luiz Henrique de Figueiredo, Waldemar Celes Filho; Software: Practice and Experience, John Wiley and Sons, 1996.
http://www.lua.org/spe.html

Lua FAQ
Frequently Asked Questions about Lua
http://www.lua.org/faq.html

Lua Programming Language
Growing article, with links to many related topics. Wikipedia.
http://en.wikipedia.org/wiki/Lua_(programming_language)

Lua Reference Manual
Reference Manual of the Lua programming language
http://www.lua.org/manual/

Luai
Alternative interface for browsing the Lua reference manual. Include overview, search facility, and extensible URLs aimed at quick access to specific parts of the documentation.
http://pgl.yoyo.org/luai/

Lua-users.org
Wiki, collaborative site for programmers; Lua-l archive, searchable body of official Lua mail list; IRC channel chat room; mini charter.
http://lua-users.org/

Programming in Lua
By Roberto Ierusalimschy; Lua.org, 2003, ISBN 8590379817. Official book, by Lua's main architect, covers all aspects, from basics to API with C; gives solid base for programmers to use Lua.
http://www.inf.puc-rio.br/~roberto/book/

Rozek: Notes about Lua
Brief description, distributions, modules, examples, applications, links; by Andreas Rozek.
http://www.andreas-rozek.de/Lua/index_en_old.html

Introducing Lua
The open source language is a useful, increasingly popular choice for embedded scripting; by Keith Fieldhouse. O'Reilly Media ONLamp.com. <small>(February 16, 2006)</small>
http://www.onlamp.com/pub/a/onlamp/2006/02/16/introducing-lua.html

Regular Expressions: Lua Shines
Brief review of language, and book 'Programming in Lua'; by Cameron Laird, Kathryn Soraiz. Unix Review. <small>(May, 2004)</small>
http://www.unixreview.com/documents/s=8989/ur0405k/

Regular Expressions: Lua Lights up Telecom Testing
Story on how most workers (developers, field engineers, support staff, salesmen) at Tollgrade Communications use scripting to add value; by Cameron Laird, Kathryn Soraiz. Unix Review. <small>(May, 2002)</small>
http://www.unixreview.com/documents/s=2427/uni1021991894316/0205h.htm

Lua: An Extensible Embedded Language
Explains, summarizes main features, with motives, code samples; by Lua authors. Dr. Dobb's Journal. <small>(December 1, 1996)</small>
http://www.ddj.com/architect/184410014/