jakyweb – I believe the “Rebbi cards” were primarily made as an alternative to collecting sports cards. Again, I don’t think boys get an incredible amount of chizuk from just looking at pictures of Gedolim, on cards or not. That said, I can’t imagine anybody would have any issues with “Rebbitzen cards” for girls… I would imagine the only reason nobody has tried that already is because they don’t think they’ll make too much money off it, as girls aren’t so into collecting cards in the first place.
As for the pictures in magazines, some have legitimate issues with circulating a woman’s picture to the masses, as HaKatan explained.