There are numerous trolley companies that charge an arm and a leg to take you on a tour around the city. But there is one that is different from all the others -- the DC Ducks. For only $30 (just a few more dollars than the Old Town Trolley and Tourmobile), you can see DC by land AND sea! Starting off from Union Station, you'll ride around the monuments and then drive right into the Potomac! While it's not dirt cheap, you get a lot more bang for your buck than those other commericalized tour companies.