I have this one
HERE. I LOVE LOVE LOVE that it is rechargeable. Love it so much that I cringe at even looking at other booklights because I might find one that I like more that can't be recharged!
It holds the charge for almost a month at a time. (I read a couple of hours a night every night with it.) If I forget to recharge it one night then I can charge it about 30 minutes and it will be full bright again. (No way to tell if it is fully charged because ther eis no battery life indicator)
I don't like it clipped on my book (or eBook) but I can set it so that I can lay on my side and it will still light up my book. Or I can lay on my back and set it on my chest.
I've used it for about 2-3 years. Hubby gave it to me for Mother's Day but I can't remember WHICH Mother's Day... I've used it everywhere including the car with no problems!
It stays charged so long that I never even bring the charger on vacation with me. Like this time I was gone about 10 days and I didn't bother to bring the charger. (I haven't got as much reading done as I'd like however because I've been too pooped at night to read!)
Anyway, I can't say enough good things about it. It has really worked well for me.