I have a friend that has a blog about grocery shopping, the food she
buys and the meals she makes. She spends about $600 a month on food
and her blog makes about $600 a month.
She says that she doesn't have to declare any of her income to the IRS
because the food that she buys is needed for the blog she writes, so
she can deduct it as an expense. So she is basically getting her food
for free because she would have to buy it even if she didn't have a
blog about it.
further discussion here:
http://www.savingadvice.com/forums/general-discussion/48185-can-she-do.html