In these modern times, it'd be hard to find work for Spartans. Because while I can see them still killing gun-toting soldiers, I can't see them doing much against tanks, helicopters, or a damn frigging nuke. But there is one job I can think of that they can perform AND have prior experience in.
Hire them as security at the Olympics.
In the ancient and original Olympic games, the authority over all - for ANY disturbance whatsoever - was none other than Spartan warriors. They'll make ANYONE behave, or it's sword and spear and shield in the face.