The Bay RSS plugin is not a free plugin, but it is a champ when it comes to including related products at the bottom of your posts.
This plugin pulls auctions from ebay, and puts them at the bottom of your post. You only have to add a couple of fields of information at the bottom of your post, and the plugin will do the rest.
You can make money from new ebay users as well as from winning auctions. This plugin is excellent for niches where there are corresponding products to your posts.
Alinks
Alinks is a neat little plugin that will automatically insert links for specific keywords in your blog. You use the admin area of the plugin to specify which keywords or phrases go with which links. You can use clickbank, CJ, Amazon affiliate links, as well as links back to pages or posts in your blog for more keyword authority for your site.
Text links are more often clicked than banner ads or any type of ads. You can automatically have your affiliate links inserted as keyword anchor text in any post, or page of your site.
Buy Me a Beer
This plugin basically asks for a donation from your readers. You can ask readers to buy you a beer or a coffee for great posts.
Do you wonder if this plugin really works? Do people really just send you money for a blog post. It does happen. I had someone send me an email and money for coffee for helping her figure out something she'd been looking for. She mentioned how much the blog post had helped her, and thanked me with sending money through paypal.
This plugin works through paypal, so when someone clicks the "buy me a beer" link at the bottom of the page they are taken to paypal where they can send you money. It's not the fastest way to make money on your site, but it does work, and being appreciated for a job well done feels good.
RSS Footer
This plugin will allow you to add more text or a banner ad at the bottom of your RSS feed. You can add anything you want, a text ad, banner ad, affiliate link, anything that can make you money at the bottom of your RSS feed.
Coming through in your RSS people may be more apt to click on a link because they already know and trust you. There you have it 4 make money plugins your site can use to increase your revenue. There are so many ways to monetize a wordpress site, it is always helpful to have a plugin make it easy for you.