Lights

So I did my first night ride at the weekend, the Dorset Dash. Bought a Hope V1 for it with a view to use it for commuting in the winter (non-lit roads).
It is great for lighting the road in the pitch dark. I found I only really needed the second brightest setting for really dark points, but when the moon was out or I was riding alongside someone else then the dimmest setting was enough (I occasionally switched to flashing when there was plenty of lights around me).
I was a little concerned about battery life, but had no issues with batteries dying suddenly, they were only Tesco's own brand so nothing special.
It's a bit of overkill on roads with street lights so I wouldn't bother spending the cash if you don't intend to head out into the dark, but if you are, then it's definately worth it!