In my seat bag I add 50 cents in case my cell phone is dead I and need to use a pay phone. The $20 can also be used as a tire patch if needed.
Also, keep an area with all your cycling materials. This helps avoid searching for knee warmers or gloves in the morning.
Air up your tires the night before. Set everything out you need.
If you use Oakely M Frames or Half Jackets, two pairs of lenses are nice. In Kansas, I might have overcast in the morning and full sun on the ride home.
I keep ride with an extra tube and a CO2 bottle, but keep a spare tube, floor pump, chain lube and rain jacket at work.
I also drive once every two weeks to bring clothes, socks and underwear to work, rather than bring my clothes everyday.