Anybody remember the report of Columbus actually making his journey a few years earlier than his trip from Spain? A pope had sent him out and even had an inscription on his sarcophagus that he had sponcered the discovery. Also an Arab map c.1488 showed the western hemisphere and mentioned a new world discovered by the indfidel from Genoa, a reference to the earlier voyage. Apparently that Pope died and a Spaniard one took over and steered Columbus to his King and Queen who sent him out again this time in their name. This move wasn't a petty thing for personal glory rather it had to do with legal claim for the plunder which went to Spain and not the church or Italy. I'll try and find that article.
I also think there was a report of Inuits visiting Scotland before Columbus's trip.