Real-time or faux-real-time stat counter a la Teamwork.com

Question

How is it possible to replicate or approximate the functionality that http://www.teamwork.com has on their home page, which essentially displays stats that seem to update in real time?

I would like to create something very similar which counts to a series of totals, but in a realistic manner, using randomised intervals.

This would be hosted and displayed in a standard HTML5 environment and would prefer not to call from a database.