Buy Pilsner Urquell, bottle deposit in Sweden is 50 Swedish øre. Drink it up and then do the deposit in Norway, where you get 1 Norwegian kroner in return. Both fun and extra money in return!
The business idea is tried before by Kramer and Newman in The Bottle Deposit, Kramer giving the details in the clip http://www.youtube.com/watch?v=x1blsZxXDCU&feature=related