Jetbeam has a single AA rebel 100 light. They say it's the same ~90 lumens that all other single AA lights are these days. Not enough oomph. However, the Jetbeam is designed to work with a 14500 li-ion 3.6v battery if you want a bright AA with short runtime and a hot case.
EDIT: I'm wrong. Apparently they've switched the LED from a Rebel to a Cree Q4 on that one. The basic premise is probably still sound though. Just not enough oomph in a 1xAA battery.
http://www.cpfmarketplace.com/mp/showthread.php?t=169263
Improved Type:JET-I MK.II R
LED: CREE 7090 XR-E (Q4 bin)
I wonder if they're going to keep the R in the name ?