I have to second Kodiak. Maybe I'm too fussy, but I find even the Arc LS shape and size too large for a pocket. But an Arc AAA modded with a Lux III by LED_ASAP is undetectable on a keyring. Mine is only just perceptibly dimmer than an Arc LSH-S, and if you could put up with less than a hour's runtime, you could probably persuade LED_ASAP to increase the current for even more brightness. Runs longer on NiMHs, too, which is just about perfection.
Unlike Kodiak, however, I've left the acrylic half-ball lens off mine. I really like the broad spill, but there's still a pretty fair hotspot. This light really is bright enough for using on walks.
Cost is in the neightborhood of $90 or so, if price is an object. If it isn't, get three of them. /ubbthreads/images/graemlins/grinser2.gif