I'd love to see a system that allows you to set clothes on the character in layers. Not set layers like "shirt goes into shirt slot which is under coat" like UO had. But actual layers that you can work on yourself. For an example having a red short sleeved shirt over a white long sleeved shirt. Or backwards. It being all up to you. No reason why you wouldn't be able to wear a skirt over the pants on your adventuress. Or a vest over a shirt and then put on a coat over that. This would allow much more customization regarding your looks and far more interesting combinations for clothes.
If clothing is layerable how much should armor be? A knight in the Middle Ages might put chainmail over padded armor (a gambeson), and plate over padded, giving him several layers of protection. It also became common to wear coat-of-plates, lammelar, or brigandine over chainmail. Chain coifs were also often underneath plate helmets.
Ahh, that is actually a good point. Should we be allowed, or even required, to wear clothes underneath armour for extra protection and comfort? I'd say in the very least we should be allowed to do so. Dear goodness armour will be heavy if you layer them enough.
@redfish I believe layering does take place in certain armor types. For example plate mail usually has some kind of chainmail shirt or at least chain covering certain exposed parts. Take a look at plate armor and you'll see it in the armpits etc.
@Isaiah Yea you're right, here's a summary of the process of putting on armor, http://wiki.answers.com/Q/What_were_the_layers_of_a_knights_armor It refers to a "heavily padded jerkin" - that's the gambeson. However, I've also read that wearing full chainmail with plate over it would be very heavy so it was common to just wear the plate over the gambeson, and chain was designed to cover the exposed parts. The gambeson, as I said, would also be typically worn under chainmail. @gingerale Someone on the forums suggested wearing fur under armor for warmth
I found a discussion about plate over chainmail here, http://www.myarmoury.com/talk/viewtopic.php?t=27859 "Monstrelet and several people at Agincourt state that full plate harness was worn over a hauberk. They state that it helped wear down the french walking across the field."