OpenSky is an online store that brings bloggers and suppliers together. It's free to sign up and bloggers create a profile which also serves somewhat like a store front.  Bloggers can then browse through the available products and select which products they like and would appeal to their readers.  Product listings display how much commission you'll make when you sell that product.  In most cases, it will be a 50-50 split of the net profits on each sale. 
Once a product has been added to your profile page, you'll also receive a link that can be added to your blog post, tweeted or placed on Facebook directing readers to that particular product. 

I recently signed up for OpenSky and I have added a few products just to get my feet wet.  I know of other bloggers that are members of OpenSky and find it to be a good way to monetize their blogs.  Visit my OpenSky store to see what it looks like.