In soccer you can bet on a draw (they don't usually use point spreads, but odds, and if your team doesn't win (in regulation), you lose. If its an elimination game which goes to overtime/penalties, it counts for gambling purposes as a draw.
I looked online but couldn't find any bookmakers offering odds on a tie in an NFL game. But if you're feeling it, I'm sure someone would give you a good price (66-1 probably).