From the article:
Lessons to Learn from Profitable Blogs
Having briefly looked at the growth, traffic, niche and revenue for these blogs, one can come to a few general conclusions. While they may be relevant to most bloggers, they might not apply to some outstanding bloggers within any particular niche.
2. The niche you choose affects how much money you will eventually make. Some niches are almost inherently easier to monetize. (Tech>Humor)
3. Highly unique blogs with interesting topics (Cheezburger) can become profitable and popular very quickly.
4. Comparative analysis will show you that you are under-monetizing or not making full use of your traffic. Despite the niche differences, Cheezburger still earns less than Go Fug Yourself, while having four times more traffic.
5. Lucrative blog niches with a large potential audience are tech, humor and celebrity culture.
6. Metablogging (blogging about blogging) will not make you a lot of money unless you are exceptionally good at it.
It's all about the niche...