Make Relish: Stir together all relish ingredients except corn in a 4-quart heavy nonreactive saucepan and bring to a boil over high heat, stirring until sugar is dissolved. Stir in corn and boil, uncovered, 5 minutes. Transfer to a large heatproof bowl and cool to room temperatures, stirring occasionally, about 1 1/2 hours.
Make Sausage Ring: Put oven rack in middle position and preheat oven to 350°F Butter bundt pan.
Pulse crackers in a food processor until finely ground. Combine crackers and remaining sausage ring ingredients in a large bowl and mix with your hands until combined well. Pack mixture into pan, pressing down to eliminate air pockets. Bake 1 hour. Carefully pour off excess fat, then unmold sausage ring onto a plate and pour off any liquid on plate. Cut into 1 1/2-inch-thick slices and serve with drained relish.
Corn relish can be served the day it is made, but is best after flavors have developed at least 1 day. Chill, covered, up to 1 month. Bring to room temperature before serving.