I bought two Cree Q5s from
ebay, based on reading and re-reading a few of the threads here. £16 for the pair and seems plenty bright enough to stop me getting lost on Glasgow Green. Quite a few of the lights suggested here have separate battery packs, and there's no way I could set that up on my bike without having the batteries in my pocket, so standalone torchlights it is.
Also they came with a free rear light, which, when mounted on my seat stem below the two dangling LED lights I got for free from a road safety stall, it makes it look like I have a sad robot on my rack....