I have seen some great promotional tools such as a promotional T Shirt or promotional keyrings that are branded with the blog or website and have the co-brand of the specific affiliate.
Also don’t forget that you need to think about your off line strategy that may include promotional caps that you hand out at conferences or trade shows in order to drive traffic to your blog or website in order to maximize your affiliate ROI. Instead of a lot of trial and error they have managers that can help evaluate your site and traffic and provide insight into what ads and links may work best for your blog or website.