The next generation heavy lift rocket - Ares V - which will be similar to the Saturn V, will be quite a bit more powerful. This monster will have the volume to lift a cluster of 8 school buses, and the equivalent weight of 16 or 17 buses. Why? Just because it can!
Either sell and old bus to a group of artistic hippies dressed in paperclips for a pilgrimage to "Burning Man" or launch them into space. I guess either use would be just as strange...
Seriously, this thing will be able to launch some pretty big space telescopes in the future, spacecraft for the moon or Mars, modules for the space station...or a spare bus.
Unlike the shuttle cargo would be going on a one-way trip since it can't bring anything down - but how often did the shuttle bring stuff back? Not very often.