Most of the ads you see on the side of my blog are from shareasale.com It's a simple ad network that accepts blogs, big or small. They have quite a few ads to choose from. You just pick the ones you are interested in, wait for the advertisers to approve your blog (sometimes this is instant), then copy the code onto your page.
I've only had them up for about a month and my ads have already generated $10.50. My blog is still quite new and doesn't have a lot of traffic yet. So $10.50 for doing basically nothing sounds good to me.
If you'd like to sign up with shareasale.com, please click on the link in this post or click on the picture (also in the post).
As I make money from blogging, I'll be sure to post the best options for new bloggers. :)