OpenKuka
This website is a community effort to provide better documentation for the Kuka Robot Language (KRL). Its goal is to become a shared tool for robot developers (industrial, researcher, student, ...).
Karl Singline
This youtube channel belongs to Karl, a really cool guy who makes detailed videos about robotics in architecture
Robots in Architecture
Led by Johannes Braumann, this forum is for anything related to KUKA|PRC. Johannes responds to most questions himself within a day or so.
Dr Stienecker's Tech Site
A concise one-page explanation of basic KUKA control language.