Another possibility, combining some previous ideas... what about a designated "employee time". Set aside a one or two hour block each week where employees are allowed to do their own stuff (side jobs) at a significantly reduced rate (essentially cost + a few percent). This way, the employee knows from the get-go anything personal done outside of that time period is a definite no-no. They get to play with the machine and try new ideas, maybe make some cash on the side, and you get the benefits of knowing they'll be happier, are increasing their knowledge base, and any extra wear and tear is measurable. You can also sweeten the pot and tell them they'll get a commission for every sale they bring in during normal operating hours by way of their experiments... incentive to try new ideas and look for new clients. The new clients are typically going to be jobs too large to run during their "employee time" block.