If anyone goes to Paris, you've got to visit a place called Angelina's, which is on the street across from the Louvre. It's a nice "salon de the" (tea room, technically) which serves hot drinks, pastries and small meals.
The thing they do best, though, is hot chocolate. It's like liquid decadent pudding/mousse rolled up into a warm creamy drink.
Go to Angelina's. You won't regret it!