All they do is provide shade

[Gidi Morris]

Well, pretty much.
Granted a lens hood can provide extra protection, but considering the way overpriced hoods were forced to buy, this can be a nice solution against lens flare.

At least until you save up the hood's price on the side :D

http://www.lenshoods.co.uk/

yup yup ;)

[Savagebasher]

white paper still reflects light. I believe most (if not all) hoods that you purchase have a black matte texture on the inside.

[dziuggy]

actually useful site for an emergency situations or back up. you can print the ones you need and keep them with some tape in your car/bag and use it if you forgot the hoods. also if you dont have a hood yet you could use this on temporary basis.

about light reflection there is no reason why you can get colored/textured paprt to prevent that or even use paint/sharpie to make it black.

no something for pros but could be useful in certain circumstances. thanks for sharing