This is for a WebInterface used to administer OpenWrt. For running a WebServer see http.overview.
You can read about WebUIs on http://lwn.net/Articles/420066/ from 2010-12-22

Mainly Lua (programming language)

• Project Homepage: http://luci.subsignal.org/
• Translation Portal: http://i18n.luci.subsignal.org/
• luci.essentials
• LuCI – Technical Reference
• http.uhttpd is default web server

Uses haserl, see also old howto on X-Wrt

• Project Homepage: http://x-wrt.org/
• howto install the WebIf of the X-Wrt project on OpenWrt
• http.lighttpd is default web server

Uses JavaScript?

• Project Homepage: http://www.gargoyle-router.com/