Where can I buy tickets in advance for le louvre in paris
http://www.ticketweb.com/snl/VenueListings.action?venueId=18803 official website that showed that information: http://www.louvre.fr/en/advance-tickets
btw, i wouldn't recommend buying them via the us/canada site (I believe it's more expensive without the printing at home option.) I'd buy them at the tourist information center, or FNAC.
such as http://www.fnactickets.com/place-spectacle/fichesalle/PARIS-01-MUSEE-DU-LOUVRE-MLOUV.htm
Buying tickets at the museum generally doesn't take long. There are lots of machines as well as several staffed windows. It's the security check before that where the lines form. To avoid them, use the Carousel entrance, not the Pyramid entrance.