You can split the output of that one regulator to as many kegs as you like with T's or Crosses or Manifolds.
Or if you want, there are "secondary regulators" that screw on instead of the gauge, they're the one you see all lined up in a row like on This Page
We need to be careful how we use the phrase "secondary regulators". On the page KiltLifter linked to with the dual regulator setup both of them are "primary" regulators capable of taking full tank pressure. A true secondary regulator might only be able to take 200psi and would need to be fed off the output (bottom port) of a primary regulator.
To add to the confusion, some companies use "secondary" for regulators that are remotely attached to full tank pressure.