So far, my favorite has been my two S-Minis (one XP-G, one XM-L). Without a battery, it's about 50 grams. Heave an 18650 in there, and it's still lighter than some 1AA flashlights! ~350 lumens, available in XP-G for a more focused beam or XM-L for a more floody beam. I attach mine to my helmet with a couple of good rubber bands when the need arises.

For beam comparisons on the S-Minis, right-click each of these links, open them in new tabs, and flip back & forth:

http://i240.photobucket.com/albums/f...SMini_XP-G.jpg
http://i240.photobucket.com/albums/f...SMini_XM-L.jpg