fluorescent from a camping shop or a motor store, eg inspection lamp. but if it was me i would go & buy LEDs, i make mine from
http://www.ultraleds.co.uk/product_info.php?manufacturers_id=16&products_id=552&osCsid=c2b833ab56750611425e019f88e1d6c9 because they are low voltage you can use lots of them, buy the holders from a car spares shop, or solder them up direct to the pins, its simple and you get loads of clean bright white light. they are not cheap to buy but they do last over 10,000 hrs on constant thats about 14 months! so if your going to spend 14 months worth of nights in your tent.... ha ha anyway i think LEDs are the future in lighting... wait and see them used in everything soon... huh i bet some one will make these up for camping ect in a commercial way, but ive used them for some time now. there is a site that sells the LED tube type like the fluorescent, but i dont know how good it is. heres the link.
http://www.litewave.co.uk/blue_led_tube.htm what i do know is that they last much longer & use lots less power so your 12v power pack wont need charging so often. buy or make the choice is yours.... go on make your own its cheaper.
the other thing is LED torches............maplin sells a pukka yellow divers torch & it takes 4 AA batteries, ive got one & its the biz.