Hi Alex,
GetARoomApp allows admins to create new "Companies" and "Users". Then, the admin assigns a number of hours to each Company that can be shared each month by the members of that Company. So, if your space has a company of 3 people that gets 12 hours of usage each month, each member of that company gets an account and can book conf room time using the shared 12 hours. If it's a solo person, we list the solo person as both the company and the only user in that company.
At BizHaus, we hate strict rules. We started off on the honor-system (i.e., book on google calendar and don't hog the conference rooms!) ... but as we grew, staff was spending too much unproductive time mediating conf room conflicts, so we had to move to an organized system. We have about nine conference rooms spread in 4 buildings and about 350 members sharing them. Each full-time members gets 6 hrs per person, open-deskers get 4 and part-timers get 2. GetARoomApp has worked well for us for a couple of years.
Hope that helps!
Keith
p.s. we're big fans of your podcast :-)