While NASA is having problems reaching milestones for their new Ares rockets—the conventional rocket that will get the US to the moon and Mars—China is actually trying to build a reactionless space thruster like the ones used by Cylon Basestars. Yes, that's science fiction, but the engine is theoretically possible. And I don't know about you, but anything that looks this cool and says "Magnetron" on its plans is good enough for me:
This is a very basic diagram of an Emdrive, a kind of reactionless drive—which "doesn't require any outside force or net momentum exchange to produce linear motion"—being developed by scientists at Northwestern Polytechnical University in X'ian. The Emdrive consists of a cavity that gets flooded with microwave radiation, which theoretically will result in linear motion as supported by Einstein's Special Law of Relativity. Or something like that.
However, some people say that while the engine is theoretically possible, as it doesn't violate the law of conservation of energy, it won't work. In any case, what is important here is that there are scientists actually working on this device and perhaps pushing the envelope forward with their experiments.