Felt washers on around control shafts.
 

I figured this is a good a place for this question as any I can think of.
I've noticed felt washers or similar on the control shafts on old wood cabinet radios. What are they for?

Possibly to keep the knob from marring the finish and to prevent a visual gap.

And to give something for your fishing flies to stick to when you start working on radios....

yep.
Used a lot for hiding the bright metal washer & nut on the threaded control shaft you may otherwise see in the gap between the knob and panel opening.

OK. That seems like that answers that one. I didn't think the felt would work to well to keep the dust out, since the cabinet is ventilated anyway.

It makes a finishing touch visually and keeps the knob from rubbing on the cabinet. I have bought new ones a few years ago from RadioDaze:

http://www.radiodaze.com/felt-knob-washers/