I've got to put in my two cents...
I think exploration is important... for the previously given examples of Megellan, Columbus, etc. I realize that all of their travels resulted in some phenomenal discoveries or accomplishments, but how many hundreds of explorers had to fail before they could succeed?
I have no doubt that there are innumerable benfits to space exploratrion, but I also realize I may not reap the benefits in my lifetime. I think simply to discover any life form outside of our planet would be the greatest discovery the world has ever seen. Though life on our planet is incredibly diverse, no two species are really fundamentally different from each other. All existing lifeforms that we know of require at least carbon and oxygen to exist. What if we find a lifeform that requires, say, only nitrogen to exist? The potential benefits resulting from research on this lifeform could be endless. Furthermore, even if we only find organisms similar to ourselves, we may discover new microbes, which are very very very important to our existence, sorry DS.
I do agree with DS on the claim that companies should be the ones exploring space. This will happen in time. The reason it has not happened yet is because companies have no motivation to go exploring in space. There are still to many emerging markets in under-developed nations for them to focus on the zero emerging markets resulting from space exploration.
I also agree somewhat on the sea exploration claim. I really do wish more research could be done on the oceans and on ocean life b/c the oceans probably hold more resources than ever resource we have available to us on land. Since water happens to be so plentiful, I really think it would be practical for our scientists to research alternative energy sources resulting from the oceans or from water.
I think thats all... I look forward to everyone's replies!