I like my Pelican L1 (and a quick comparison)
The clip is handy, so you don't HAVE to carry it in your pocket. You can just clip it onto something that you always carry, like a coat, backpack, waistline of pants, pants pocket, etc.
Also, it is hella-bright. Many consider it a huge drawback that it runs off of xx76 or xx44 batteries, but they give a long life for a pocket light, much longer than a single regulated AAA.
FOR PELICAN L1 OWNERS:
It can probably be boosted even more by replacing two of the cells with a two-cell xx76, replace one cell with a nut of the correct thickness, and leave the last cell unscathed. As you might suspect, the double cell will yield more than double the capacity of two single cells because they're not forced to use valuable space with the case of the battery; more guts! The missing cell should promote a smaller current draw and even more battery/LED life. (or if you're not worried at all about shortening the life of the LED, you could replace the button batteries with TWO of the double cells...)
Now I don't know if there are Lithium AAAs yet, but for the button cells which the L1 uses, they can be replaced by the more expensive silver-oxide cells which will yield more burn time at high power and better resistance to cold. Has anyone tried any of this with their L1s? From an affordability standpoint, the L1s go for about $14 or so. They can be carried on a keychain like the Arc AAA or clipped on the bill of a baseball cap for an impromptu headlamp.
As you can no doubt tell by now, I'm smitten with mine. I think it is the most versatile pocket light out there.
Last but not least, I will have to admit that I don't have an Arc AAA yet, but I'm going to remedy that as soon as I get a respectable 4AA or 3C light...
-Jeremy
PS - Great thread!