My favorite Ruby Kaigi talk was by Yasuko Ohba (@nay3) of Everyleaf Corporation in Japan. Despite the fact that the talk was in Japanese, with nice code examples on the slides and key translations over IRC, I was able to follow the presentation and learn some tricks. The coding techniques are really quite straight-forward, just not necessarily intuitive to invent. She reviews a variety of techniques along with real and imaginary examples of each.