Direct marketing is another popular method for bloggers to make money off of their blogs. This requires more work than just setting up an account with Google and smiling, or frowning, at whatever ads show up.
In this case, you need to either accept - assuming someone's offered - or look for a company to partner with. Then that company or individual pays you to place their ads directly on your blog. For the advertiser, they get to specifically target an audience - YOUR audience. For you, this option is great because you have a sure source of income from your blog that you've hand-picked. You no longer need to hope for the best with AdSense, although it IS pretty good about matching ads to fit your content.