Learning the Yaku - An attempt to break down the many yaku of Riichi Mahjong in an order that is more accessible to a new player
EMA Rules PDF: At one time, I had a copy of the EMA 2016 rules here, with some typographical issues fixed. Happily, the 2025 edition has made this redundant, so access it directly from the EMA's site.
Tenhou Stats - some tools for rendering and reporting on games played on tenhou.net