In an article about crossing railroad tracks, CycleDog explains the proper method is to ride perpendicular to the tracks to avoid a faceplant. Trials rider Ryan Leech demonstrates the New School way to cross the tracks in this video (16 seconds, Windows Media, 488KB).
I tried bunny-hopping over the numerous speed bumps in the parking lot at work back when my Bianchi was new. But Ed's Vertical Crush Test led to far too many broken spokes. I weighed about 225 back then, and the bike tipped the scales at about 40 pounds when lights and baggage were installed. The 'pow!' of a spoke snapping was a weekly occurrence.
So I don't bunny-hop anymore. Besides, it looks odd when a decidedly middle-aged man starts jumping up and down, can't get his feet out of the pedals, and topples over, then flails around on the ground still firmly attached to his bike! I have an image to maintain, you know.