I'm a klutz, so I'm no stranger to falling. I fell on my brand new bike the day I bought it, in the parking lot of the LBS as I planned to ride home on her. Couldn't unclip the road pedals and fell. I fell 3 more times in the those pedals because I just couldn't get loose, so I took it back and switched to SPDs. I still sometimes forget to unclip and fall over, always in slow motion.
I also went down pretty hard going under a bridge crossing after storm. It was shaded by trees on each end and dark as it's an under pass. I didn't see the mud slick that covered the trail from one side of the underpass to the other. The trail turns and drops down into the underpass, and I was doing around 25 mph when I hit the mud and slid for literally 30 feet - it was like a slip and slide. I was covered head to toe in a thick layer of black, slimey mud, 6 miles from home. At least it was the last 6 miles of my 30 mile ride! Fortunately, the mud "broke" my fall, so other than being a little bruised on my elbow from hitting the ground, I didn't have any road rash. DH had to get the hose out and hose me down once I got home, peeling off the mud.
I have campus pedals on my commuter - SPD on one side, flats on the other. I also wear moutain biking shoes when commuting so I have more grip on the foot than my road shoes offer when I do step down. I also don't have to worry about missing my cleat when starting off because I have a flat base either way and can go. Makes it a lot more comforting.