My preon REVO blows people away with the brightness for the size. Just lit up a friends back yard with it last night. It's not brighter than many other good AAA lights, but when you also start taking people through all the features (current control, strobe, SOS, beacon modes, almost 3 days of run time on low etc.) they are pretty impressed that all that is in a tiny light that can disappear in your palm. Also sticking with out-put-to-size impressiveness is the Zebralight SC600 that has been mentioned by others in this thread. Barely protrudes from your hand but with 750 very floody lumens it lights up everything in front of you, and still throws very nicely out to 150 meters or so. There are brighter lights, but to get anything significantly brighter you need a light twice the size, which becomes less impressive.