XenForo powers everything you see there (aMember will be added later as well though).
From a developers perspective the code has a few hacks here and there but ultimately the whole website is very manageable (helps that I have a custom dev -> test -> prod deployment system integrated into XenForo). Any developers looking for a new platform... this is it!
From the end user... the main areas might seem to be lacking a XenForo integration. This is because I am separating customers from forum users, much like XenForo Ltd does here. However, as explained here, a temporary system is in place which is why I was able to get the upgrade out there. When time permits, aMember (a highly customized aMember tightly integrated with XenForo styling and JS) will power the customer section of the website.
The forums are a customized version of a XenFocus skin.
The rest of the site was designed by Rhyl Mayes who took the colour scheme and went with it.