We Canucks swear by Cold-fX. In the winter we pop them like vitamins and use the individual packs for those awful summer sniffles. It's as close to a cure to the common cold as anyone's ever gotten.
To all the non-believers out there - this thing works! When I feel a cold coming on, I start taking some of these pills and *poof*! It boosts the immune system, and I never fully develop the symptoms! Heck, it's worth a try everytime, because we have a looong cold season up here!