There is a wealth of things to see in the Louvre that are not the Mona Lisa. There are innumerable beautiful sculptures, enough to drive you mad. One could spend a hundred days staring at each of a hundred statues, and not have exhausted the statues worth spending a day staring at them, and learning everything one can about them.
One of my favorites, I actually can't find a picture of, it is very sad. It is an early middle ages statue, on the opposite wall of this statue:
There is a similarity in the grotesque nature of the statues, but the one I most admire is a dark stone, reddish brown, meant to adorn a tomb and remind those who might dally around the church of mortality and death. At first glance, the pose is almost sensual. A tall, lean figure draws his or her robe apart from the middle, like curtains on a day. On closer inspection, we find that maggots are crawling from the belly, the ribs are showing, and what we thought at first glance was a broad smile is the grin of a skull. Creepiest statue.
This is, of course, only one of the innumerable works. If you wish to discover them at more leisure than I had, I highly recommend the Louvre website:
Though not as complete or detailed as the Google Arts Project website, it is nonetheless a great way to see a fair bit.
Also, I seem to have an affinity for sculptures made of two different stones: https://picasaweb.google.com/lh/view?q=louvre+medieval+sculpture&uname=110928301193705058443&psc=G&filter=1#5401926538412404642