I read about this online a fair bit. For instance, bloggers who ask for payment to do product reviews or cover brand campaigns remind brands that ... the free stuff doesn't pay the light bill or put gas in the car. They also mention their commitment to the hard work of having a blog or of doing what they do. They have learned to be their own megaphone - "I'm a writer, I work hard at this blog, I pay attention to industry needs and new technology, and the time I spend covering brand events, products or services, is worth being paid for. I am not 'just' a blogger."
It's great to see the kind of chatter around Facebook, Twitter, blogs, and other social media. It's encouraging to hear bloggers help other bloggers answer the question, "what do you say when a big brand wants you to write about them, and in return they'll promise free traffic on their big-name site?"