I have added Amazon Context Links to my blog. The links will show up with a double underline. This links are automatically added by Amazon, linking from content in my blog to Amazon products for sale. These links provide advertising to help pay for this blog hosting.
To add them in WordPress, I first went to the Amazon Associates Central. Their “Context Links” page under “Build Links” page provides an interface for building the snippet of code needed to add Amazon Context Links to the site. I copied this chunk of code to the clipboard. Then, I opened the theme’s footer, which in my case was: wp-content/themes/default/footer.php. I pasted the code right before the <?php wp_footer(); ?> text at the end of the file. That was it. We’ll see how this works.