Over the last couple of years I have developed a multi tenant content management system with integrated online store and booking.
getya•net is currently used daily as a business critial system by e.g. alternative clinics and online retailers.
The technically interested will love that it runs on Microsoft’s advanced Windows Azure cloud offering in a redundant and automatically scalable environment.
Have a look at https://getya.net. Though the page is in Danish, I’m sure you can find the trial sign up link in the green box. Go ahead, the rest of the site is in English.