Garth Goode posts a nice blog entry about a dinosaur museum in Second Life that I had to check out. It appears to be based on the Museum of Natural History in Vienna, Austria, although there is almost no information provided in the build. The way that the museum creators incorporate photos of the real life museum is really amazing. You get the sense that your avatar is moving through the actual museum through the clever placement of actual photos of the museum.
Check out the quick machinima video I took, which gives you some flavor of what the experience is like.
Or better yet, just head to this teleport link to visit it for yourself.