These are fairly "spendy" for a small flashlight, but they will clip onto a baseball cap & work for reading & working. My wife used one when we went into a lava tube up in Flagstaff for a "hike" last summer.
You don't need to spend $40 for a reading light, but they work well enough & last a long time with the single CR123 battery on low power. They also have a magnetic base & will function as a work light in a pinch at night or under the truck. They are small, compact & weigh next to nothing. No, I don't work for the company, just like this light!
http://www.amazon.com/Olight-S10-LED-Fl ... B0091QBCK6Edit: Better deal from Amazon
http://www.amazon.com/Olight-S10-Flashl ... J6CEPXGTJR