Trousers. Was wearing shorts that morning for the ride. Borrowed a pool car to drive home and pick them up.
Gloves. Got 5 minutes down the road and realised that I wasn't wearing any. Had to be the day that I fell off and put a big dent in my palms, didn't it!
Forgot my lock recently, but got away with it. Work isn't a problem, supper I ate outside, alongside my bike, at a place that was inside, so didn't get cold either, and had got friendly with some people at language school, so two-upped with a lock there.