Reply #5: I hadn't thought of it that way, but it's true that only men wear the special headgarment

[foo_bar]

Even in "Reform" Judaism (reformist by 18th century Prussian standards) I can't say I've ever seen a woman wearing a yarmulke, or even a female rabbi (although "Reconstructionist" Judaism or whatever it's called nowadays permits both (along with gay marriage and gay/lesbian rabbis), but they're a tiny minority compared to the various Orthodox movements) (and "Reform" in one locale might be more conservative than "Orthodox" in other places so it's difficult to make much of the labels; there might be Reform congregations where women are allowed to wear t'fillin and whatnot, but I wonder how many women even want to dress up like 5000 year old men). Can't speak for the Sikh faith, although there's some interesting theological disputes in that vicinity:

Digambars believe that women cannot attain moksha in the same birth, while Svetambars believe that women may attain liberation and that Mallinath, a Tirthankar, was a woman. The difference is because Digambar asceticism requires nudity. As nudity is impractical for women, it follows that without it they cannot attain moksha.<53> This is based on the belief that women cannot reach perfect purity (yathakhyata), "Their lack of clothes can, therefore, be a hindrance to their leading a holy life". The earliest record of this belief is contained in the Prakrit Suttapahuda of the Digambara mendicant Kundakunda (c. second century A.D. ).<54>

http://en.wikipedia.org/wiki/Jainism