I actually have three of the
Dealextreme lights on my keychain, all running higher-efficiency LEDs from the Jeled eBay store (such as
these). I have one clear DX light with a white LED sanded down flat (pure flood), another (also clear) focused, and for my third I bought some
2032 coin cell batteries from DX and swapped in a Jeled red LED, and put that into one of the black DX keychain lights. My original intention was that those would be good for night vision, but they actually too broad spectrum for that (looking at them with a DVD, I can see a significant amount of yellow and even a tiny bit of green in there) -- though they are much less disturbing to others than the high intensity white ones, and for lighting up a pathway, won't impact night vision nearly as much as the white (even though they wouldn't work for say reading up close and keeping night vision).
I also have a Fenix L0D CE on the way. 4 Lights on one keychain, all ridiculously bright.