One can really earn money through blogging; it’s either through selling products of other people, also known as affiliate marketing, or selling your very own product/service. Either way, there are various Ecommerce plugins available that can make it easier for you to sell your stuff online.
I personally use the WordPress eStore plugin and it works really well. It does take a bit of getting used to and set up, but the support from the owner has been excellent.
Here are some links that I have collated that can tell you the best Ecommerce solutions around.
10 Best Shopping/Ecommerce Plugin Solutions for WordPress by WebCoreStudio
Collection of Free Ecommerce Starter Kits for WordPress Users by GuiDesigner
10 Best WordPress Plugin for Ecommerce By Partho, Gaea News Network
7 Powerful Shopping Ecommerce Plugin Solutions for WordPress by WPTemplates.net
37 Shopping Cart Options for Developers by Vandelay Design
Ultimate Ecommerce Starter Kits for WordPress Users by WebDesignBooth
8 Interesting CMS for e-commerce websites by Antonio Luppetti
16 Powerful and Open Source E-Commerce Applications by SSL matic
Top 5 Online Shop Solutions by DevLounge