Wright Flyer
We went to the Franklin Institute today. Saw the Wright Flyer, which was pretty cool. But I'd say I'm disappointed that I learned more about the plane from the Institute's website than I did from visiting the museum (other than actually seeing it, that is).
Anyway, here's another excellent bit from Jeff Jarvis.
UPDATE: One of my housemates took some pics of the visit to the Franklin Institute. And check out her blog's main page (scroll down) to see some cool 3D renderings she plays with.