We had a croquet field set up at our wedding. Nobody actually played except for the kids, we were all to busy eating, drinking, and making merry, but I thought it'd be a cool idea and many other people did too.
If you're less into motion and more into mental, you might try Balderdash, where one person (the judge) announces a word and spells it, and everyone writes a fake definition for it, while the judge writes the real definition. Then the judge reads all the definitions out loud, and the group casts votes for which one they think is the real definition. Whomever's definition wins the vote gets a point for each vote, and you can decide amongst yourselves how many points it takes to win.
Also, you can place a board game as a centerpiece at each table at your reception. Then your guests can play the game and the winner can take the game home as a favor.
These are some ideas, hope they help!e