Well, this interesting little tidbit just crossed over the Twitter, coming from ESPN's Adam Schefter.
Vikings will play a home game at Wembley Stadium in London sometime next September. Announcement coming at Tuesday's owners meeting.— Adam Schefter (@AdamSchefter) October 14, 2012
September seems awfully early in the season for this to take place, which I guess means that the Vikings can count on an early bye week in the 2013 NFL season.
Next year's home opponents for the Vikings (outside of the divisional games against the Chicago Bears, Detroit Lions, and Green Bay Packers) are the Philadelphia Eagles, the Washington Redskins, the Cleveland Browns, the Pittsburgh Steelers, and whichever NFC South team finishes in the same place in their division as the Vikings finish in the NFC North. (For example, if the Vikings should win the NFC North, they would host the team that wins the NFC South this season.)
That info comes from the folks over at Johnny Road Trip.
So, the Vikings will be playing one of their home games 2013 in jolly ol' England. It wouldn't surprise me if it was one of the two AFC North teams, and would surprise me even less if it were the Steelers. All things being equal right now, that would be my guess for the game we'll see in London in September of next year.