Ads on Blogs

When I first started blogging, it was only for fun. Don't get me wrong, I still enjoy doing it, but now I have ads on it. At first, I remember thinkign to myself "Who would ever put ads in their blog?". Over time, I began to rethink things. The ads in my blog don't generate much of anything, but a little is better than nothing. It's my blog, can't I do what I want with it?