I definitely agree with the whole nocking thing. Once you have an arrow nocked on the bow, you will be able to shoot straight away, even if you have been knocked down after being hit (as it stands, being hit seems to be a cue for taking the arrow off the bow

).
Some other, minor things that don't warrant a thread:
Bow tremblingInstead of having a random element every time you shoot, which isn't really that fun, there should be some minor trembling of the archer's arm (surprisingly little is needed to seriously affect the accuracy - about a centimetre off when aiming can lead to up to a metre off at 18m). This would mean that, with sufficient skill, you may be able to counteract the effects of having a low archery skill by moving the mouse in a different direction. When riding on a horse, the effect would be greater. As your archery skill, PD and Strength increase, the effect lessens.
Limited draw timeAs it stands, you can draw the bow for an unlimited amount of time (of course, it's only accurate enough for melée by about 5 seconds). The more powerful bows (PD3 and above) should only let you draw for about 10 seconds (if you have a PD of 5 or so). Coupled with the above, it could make archery more versatile - that is, you can hold it for longer if you can counteract the trembling, instead of letting go after a second or two because the current aiming system makes chance come into it.