Well, forgive me the whole, "the indians were here first" when I say that I'm a big fan of Chris Columbus, but according to How Stuff Works, it may well have been an Irish monk who sailed to America before any other Europeans.  About 30 years ago, a guy proved that he could make the voyage in the same kind of boat that the monk would have used, and the Viking lore makes references to it.  Far from provable with the current evidence, though, I'll leave you to make up your own mind.