PrestaShop - Open-source E-commerce Free Software
PrestaShop is a professional e-Commerce shopping cart software that you can download and use for free. Having a very powerful back-end, store admins can manage the inventory, orders, customers & payments easily. System never limits you as it supports unlimited categories, sub-categories & image pictures.
I am an English Moderator on the Prestashop forum, and I see many people that are far less tech savvy than me that manage to install and customize their own shops, and install themes, modules and modification with little or no help.
I have many useful modules for Prestashop on my store (http://www.presto-changeo.com/), like a filter module, a translation module (which I used to translate my site to 15 other languages), and an attribute wizard module that lets you customized your attributes similar to apple’s website.