Just added a new polished aluminum shift knob which replaces my illuminated shift knob. I like the feel of the polished aluminum much better than leather. This polished aluminum knob is also shorter than the illuminated knob, so the shifts between gears feel a lot sportier.
Update: Jon Maddux sent pictures of some additional BMW shift knobs and their BMW part numbers. There are several kinds of “chrome” shift knobs available from BMW. They have subtle differences, but before you drop $70+ on a shift knob, they are worth noting. Note that both “bright” knobs are plastic. The brushed and matte knobs are solid aluminum. Ron Styger reports the weight of the different knobs are .081kg (25-11-1-434-003), .079kg (25-11-2-492-481), 0.132kg (82-23-9-405-686) and 0.128 (25-11-9-416-257). Retail prices are $85 for (25-11-1-434-003), $65 for (25-11-2-492-481), and $98.25 for (25-11-9-416-257).