Peak makes the Baltic single AAA light and it uses an underdriven LuxeonIII LED. You can specify five different output levels to balance runtime VS brightness. I have two of them, a normal HA-III aluminum one that will run over 90 minutes in regulation before a looooong tail of light until it is dead after about 24 hours on alkaline. It will stay in regulation longer with a NiMH AAA rechargable.
My second one is a stainless steel version with the 2AAA stainless body and momentary switch. It has the highest power option available and I strongly recommend not getting it if you plan on using alkalines.
Peak rates them in candlepower and there are five levels of 50cp, 75cp, 100cp, 175cp and 230cp. Plenty of kick with the 100cp and the 230cp version on NiMH is pretty insane for it's size. Give them a call and tell them specifically what runtime and battery you plan on using, they can tell you the power level you need. They cost $49.95 in HA-III aluminum or brass and $59.95 in stainless steel. The 2xAAA body is an extra cost item but will increase runtime and brightness by around 40%.
The other option is the new Fenix L0P SE which has three-stage switching to extend runtime. The regulation is poor on alkalines but very good on NiMH or lithium AAA batteries. 4sevens has them for $39.00