Just a quick post to list a few resources for LuaTeX.

Mailing lists

1. dev-luatex: the mailing list for LuaTeX developers at http://www.ntg.nl/mailman/listinfo/dev-luatex. This list is frequented by the team who are building LuaTeX and is ideal if you want to stay at the “bleeding edge”. Great for notifications of code updates.
2. lualatex-dev: the mailing list for LuaLaTeX development at http://tug.org/mailman/listinfo/lualatex-dev.
3. luatex: general discussion of LuaTeX and probably most suited for user-type questions http://tug.org/mailman/listinfo/luatex.

These lists are a fantastic resource but remember that your questions are being answered by people who are willing to share their considerable expertise, and their time, for free. A little courtesy and respect goes a long way towards getting the help you need.

LuaTeX Wiki

Code snippets and more at http://wiki.luatex.org.

Other sites

Great site from Patrick Gundlach with lots of code fragments. In German only http://www.luatex.de/.