Does your blog have a custom developed theme? If so, why not look at selling the theme template? There are loads of marketplaces where you can sell your theme, including Mojo Themes and Theme-Forest.

Advantages: This is a really quick way to make some money. If you've already developed the blog theme then it will just be a case of making a few tweaks to the admin side of things, cleaning up some of the code, and then submitting it to a marketplace - you could even sell it directly on your blog.

On top of this you can offer extended license sales that can be used across multiple sites for a higher cost to make even more cash.

Disadvantages: I custom developed the Find My Blog Way theme and was going to look at selling the theme but I didn't want to have other blogs appearing on the web that had the exact same style as my blog. I felt like it might lose its individuality.

On top of this, there could be extra resources/time needed with adapting the theme for new updates, bugs, etc.