not on my blog

I have come to notice that my blog is being used for advertising. I find this highly unusual, but also admire the people who thought of it. They post a comment on my blog that goes something like this: "Juliet you've got a great blog here....check out my cheap perfume site." I don't mind cheap perfume ads...I just don't really know what they have to do with my blog. I will see how this develops and what kind of advertisements I receive. Maybe I should charge banner space?