Yeray Cabello's blog

DeFuncto My little monster
Monads explained in C# (again) This was my first FP tutorial
F# For fun and profit The best way I can think of to learn FP without noticing it
Functional Programming - Don’t fear the monad
Introduction to TDD (She claims that productivity eventually goes up, that’s only true if you have software with a high defect ratio)
Outside in TDD
Katas from Corudance