I've spent some time over the last few days playing around with Drupal (an open-source content management system) and I have to say that so far I'm extremely impressed.
After getting to grips with its capabilities, I decided to setup an online demo shop - Retro Game Shop - powered by Ubercart (a popular open source e-commerce suite for Drupal).
The results were very pleasing indeed - after just 2 days of tinkering, I now have a fully-functional online shop up and running.
You can expect to see more products and content added to the site over the next week or so, and once I'm happy with it I'll no doubt be adding it to my ever-growing portfolio.