One could anticipate that old satellites might have enough gold and other precious metals for a new age of space scrap pirates. Pirates with privately owned retrieval craft, cleaning up abandoned craft. Freeing up the orbital space around Earth. This industry would be a scurvy one and then lead to a space scrap colony on the moon, without question.
The gravitational forces create geothermal energy. Io has been said to be "turning itself inside out" every few hundred years, although I'm not sure how accurate a depiction this is of the activity observed on Io. There certainly have been large volcanic plumes observed by previous probes.
Well, I was certainly talking out my ass about Saturn's magnetic field being used as a source of power =D However, thermionic nuclear power sources have been used for decades. If you could prevent yourself from being buried in sulfur, Io would have tremendous geothermal energy. To be more accurate, the systems of Jupiter and Saturn do indeed have a fair amount of power in different forms that can be tapped into. For example, the gravitational forces induce a lot of heat, especially in the moons close to the planets in orbit.
For one thing, it would be useful as a source of propellant in moving materials in the first place. Locally and back to Earth.
Shipping tons of hydrocarbons to earth would certainly be a waste of time, in the context of using it as a combustible fuel in our atmosphere. Look at it as a resource in other ways. How about a valuable local resource for generating new materials. This is just one compound of many, sitting there, with plenty of energy on hand to use.
Unclaimed hydrocarbon rain on Titan?! Europa is a giant ball of water? Jupiter and Saturn have magnetospheric energy strong enough to power as many crafts as we would like (positioned accordingly of course) Not to mention the added bonus of a radiation shield from solar wind and CMEs. Somebody build a station in orbit for local planetary exploration already. Oh, and the ISS is being used as a lab for experimentation, another station is needed for this as the ISS is busy enough as it is. It's not like we have to build something on the ground and launch the entire payload anymore... seriously lets go, private industries are not dependent on international government organizations for delivery of payloads into orbit. This is nothing new. I'm sure many people would be willing to take their chances in orbit around Titan, or even explore Jupiter's moons with current knowledge of the radiation belt locations of each planet.