There are a lot of superhero miniatures rules out there — both free and commercial. So if you want to try one without going to all the trouble to paint some minis, you could try some of the paper figures on this page.
Matt Fritz has some good instructions for drawing your own paper soldiers. This would be a good way to try out a new period!
Germ’s World has a large number of 25mm modern buildings for you to download and use in your modern miniautures wargames.
It’s the strangest thing: 25mm – 28mm scale paper models of …. books. No. Really.
Stoelzel’s Models offers a free paper model of a derelict commercial building.