IMO Just about the best single AA light out there for the price, output, runtime, multiple battery usage, is the Fenix L1D CE. I'm using the 2AA model L2D CE and the output and runtime are incredible. https://www.fenix-store.com/index.php?cPath=22_55&osCsid=6e111de46ffe009909033a0caa3e5882

I've also been thinking of getting one of the new (rev. 2 I think) photon protons DR was referring to. Seems like a truly useful light. I think brightguy.com has them on sale for under $50.

Another headlamp/angle light that looks interesting thats supposed to come out soon is the Zebralight, a single AA Cree headlamp with a flood beam. Don't know all the details yet but following the thread at CPF if it lives up to expectations it could be a great light. http://www.candlepowerforums.com/vb/showthread.php?t=166258&page=3