I do a daily multivitamin at the suggestion of my doctor. I also take Glucosimine Sulphate in addition to my prescribed arthritis pills, again at the suggestion of my doctor. Other than that, I'll chug down a Whey Protein shake after a particularly hard ride, but that's about it.
OTOH, I usually have bananas, apples, oranges, or some other fruits around both at home and at work. If I'm feeling the need for something crunchy, I'll go for a South Beach Diet high protein bar. It's got the best bang for the caloric buck, as far as I'm concerned.