Mighty Bright Travel Flex. It's a great light and requires only 1 AAA (I use rechargeables which last for ages between charges).
http://www.amazon.co.uk/Mighty-Brigh.../dp/1935009362
Apart from that, the Kobo Glo looks okay. Personally I'll stick with my travelflex for now. The only issue one should be aware of is that it may not be compatible with all cases.