Are you looking for a free shopping cart for WordPress? I have tried eShop, WP eCommerce, etc. which all had problems or were not user friendly. Recently, I searched again for a free shopping cart for Worpress.
This time I found JigoShop. Jigoshop was easy to install, user friendly, and had just the features I was looking for. You can sell downloads, real tangible products, and virtual products.
I use PayPal as my online merchant of choice. This was easy to configure in Jigoshop. This shopping cart uses plugins, widgets, and shortcodes.
I have a shopping cart widget enabled on one of my WordPress sites. Also, I use shortcodes on pages to list featured products. Jigoshop includes a related items feature bulit in.
This shopping cart takes care of inventory for you. You can set a specific inventory amount. If you don't want to change inventory amount but want to list a product as "out of stock", then you just have to uncheck that option for a product.
There is even a setting to turn on or off back orders. Do you still want to display Google ads on your product pages? Well Google ads still show up on each products page with currently installed theme.
This by far was easiest and most functional free shopping cart for WordPress I have found so far. A free shopping cart like this might be what your looking for to sell basic downloadable, virtual, and tangible products. If your looking for a free WordPress shopping cart that works out of the box, so to speak, you might want to try JigoShop.