If you’ve an STI or WRX, I’m sure you’ve either looked at or purchased aftermarket shift knobs (or even purchased SPT versions).
Here are a few that appear to be worthwhile to own.
http://fastwrx.com/kadeshkn.html (in fact, Mach V has a crapload)
http://www.killerbmotorsport.com/index_files/DelrinShiftKnob.htm (5 listed here)
I’ve a very heavy Razo knob that I used in my Eagle Talon awhile back, but the threads are different between the cars, so I can’t use it in the STI. I might find a new one and mount it in my car, though.
The cool thing about Delrin is that it won’t get hot or cold like metallic knobs typically do (but I tend to like metallic knobs better).
There’s also Flossy knobs, but I will not link them. Flossy shift knobs are highly desired, but I wouldn’t order one directly from the vendor, because customer service sucks to the point that you might not ever get your knob (it’s a crap shoot). If you want a Flossy, I recommend you check for For Sale ads on Craigslist or your favorite Subaru forum F/S threads. Order directly at your own risk.
Do you have a favorite shift knob? If so, share the maker/model!