Looking for an LED driver

I'm looking for a constant current (preferably adjustable) LED driver that can run off of a single AA battery (0.8 to 1.6v input) and light up 1 white LED (3.3v Vf). Does such a chip exist? I'm new to LED drivers so I'm not even sure how to search for it. Alternatively I could just use a 5v step-up converter and a resistor, but that burns away some power. If you can find one with 2 outputs that would be even better. I'll be ordering on Digikey.

Google for "joule thief"...

Ok, it's not current regulated, but with only one battery you need some sort of booster before you can do anything much.

Ha, I hadn't thought of using a joule thief actually, I remember making one of those a few years ago. But I was hoping there's an LED driver with a boost converter built in. I did find a few chips, but the output current decreased as input voltage decreased. A joule thief might be the way to go. I'm waiting for my first oscilloscope to arrive, so tuning shouldn't be a problem.