In reply to Dingerbell:
I have a Petzle NAO, which is very bright and proved very good,over the last couple of years, though it comes in at a fairly hefty price tag. I tend to use it more perhaps because it's easily recharged.
I picked up a black diamond cosmo recently because it was cheap (£15) from a major retailer, and I have to say I am pretty impressed with it for the money.
All other head torches I have owned have been rubbish, but I expect that's more to do with LED technology improvements in the past 5 years.