Presumably the people reading your blog have similar interests or circumstances to you. So you could ask yourself what kind of ads or other stuff you'd want to

Presumably the people reading your blog have similar interests or circumstances to you. So you could ask yourself what kind of ads or other stuff you'd want to see if you were the reader. YCombinator seems to be a good example of monetizing what is more or less a <a href="http;//paulgraham.com">blog</a>. I guess the generalization would be to start a business that you and your readers would like to use. Other than that, I think there's a perception that web ads are sleazy and that clicking them will lead you to someone who is trying to rip you off. The ad either needs to be from a known company, look like it was made by real humans instead of a corporation, or be from sponsors you know the site owner has dealt with personally be cause s/he sells hir own ads. Come to think of it, maybe some of your readers have things they want to advertise.