> I honestly doubt that you are getting much
  > real benefit from them either (unless you have
  > a real, medical deficiency)

For stuff like Vitamin D, it depends on where you live. For example, in Portland, OR[1], it's very sunny during the summer months, but there is very little sun during the fall, winter and spring. I remember reading that even if you spent all day out in the sun during the summer months, it would be impossible to store up enough Vitamin D to last the rest of the year.

And on the 'real, medical deficiency' front, there are many debates as to what optimum levels are for some vitamins and minerals. Nutrition is the one area where some things seem very unsettled (e.g. All fat is bad! No wait only some fat is bad! No wait eating fat doesn't necessarily make you fat! etc). [ And even then a real, medical deficiency may just mean that your body is degrading vs. operating efficiently. E.g. maybe taking Vitamin X will help your body digest and absorb food better, but you don't need it to keep living so there is no real, medical deficiency. ]

[1] Used Portland as an example, because I remember reading about this.