Not familiar? The original SaiMoe was a yearly bracketed tournament in which people vote for the (usually) female character who they consider to be the most “moe,” based on nominees from 2ch. Moe is a pretty tough concept to define, so as you might imagine, it mostly winds up being a popularity contest. That competition has been running since '02, and past winners include Sakura Kinomoto ('02), Nanoha Takamachi ('05), Suiseiseki ('06), and last year's was Lucky Star's Kagami.
The SaiMoe competition Hikikomori is discussing is the International SaiMoe Tournament, which took the same idea to a global scale-- you can keep tabs on it in English, Spanish, Portuguese, Dutch, Chinese, or Korean. Good times!