Terry Austin sent me a link to a company calling itself "Tank Limo" which claims to rent out a limousine built out of an armored personnel carrier. Terry says, "I can't tell if they're serious or not, but if they're not, they've done a lot of photoshop work."
My first thought was that there was no way a tank limousine could be legal. I was living in San Diego when Shawn Nelson commandeered a tank from the National Guard Armory and drove it around the city, crushing cars and plowing over street signs, before the police finally managed to stop him -- and kill him. So, recalling that incident, I couldn't imagine any government would let a commercial service drive a tank around city streets.
But the site looks pretty convincing to me. I found a quotation in a Mail on Sunday article from June 17, 2007 about a British tank limo service (I'm not sure if it's the same one). It says, "The idea came up after a Fifth Gear investigation into which vehicles can legally travel our roads." So maybe tanks can legally be driven on British roads. But they're sure not about to allow them in San Diego.