For those who like a very small and lightweight light for emergencies such as fixing a tire take a look at the LRI Photon Rex rechargeable keychain light. It is available on Amazon for about $17 and puts out about 40 lumens maximum by my estimate which is based on comparing it with other lights of about that claimed output. Very bright for the size and price IMO. Brightness is adjustable and it has flashing modes available too.
It now has an accessory kit available that includes a solar charger, a USB charger and a headband light holder. The accessory kit still costs a bit more than the light at about $20 + shipping. I like the idea of having the solar charger which allows light recharging without access to other power sources.