Andrew and I had the idea for Kerrb after a number of frustrating and costly incidents with leaving development VMs running for days, weeks, or even months accidentally. We wanted a personal cloud guardian that would turn them off for us if we forgot to. Now your boss won't wince in fear of huge bill when you ask for a set of VMs in the cloud to develop on.
Many people that I talk to cite expense as a primary factor for not moving their development environment(s) to the cloud as hosted virtual machines. When I probe further, this is usually because they have to remember to suspend/shut them off when they are not working with them. What better solution than to let someone else timer to automatically suspend them when they are not in use? Hence Kerrb is born!