Ok, I think I have the whole thing worked out, and I have now done it on two keyboards:
Start with a Coolermaster Storm Quickfire Rapid keyboard.
1. Grind off nubs on J and F keys with dremel and grinding tool
2. Wet sand logo on spacebar and windows keys with 400 grit sandpaper until completely gone
3. Wet sand each key individually to remove texture and enough of the letter paint that you can no longer feel it.
4. Wet sand everything with finer sandpaper. I went straight to 2000, but something intermediate first would have been better
5. Use dremel tool with felt tip to polish each key to a shine. It doesn't take long.
6. Remove plastic dust and felt residue from sides of the keys and rub everything with a soft cloth.
Voila! Perfectly smooth and shiny keys with no bumps and no annoying logo on the spacebar or windows keys. It was a lot of work but it was so worth it.
A couple of notes:
* I did one keyboard with dry sanding and the other wet. Wet went faster, was cleaner, and didn't gunk up the sandpaper as much. Definitely use water when sanding.
* On one keyboard I skipped the 2000 grit and went straight to the polishing with felt. That keyboard is not as shiny as the other. They are both shiny enough for my taste, though, and my fingers are very glad I didn't put them through another punishing round of sanding.
* When using the felt tool and the dremel, be sure not to leave it in one place too long or the plastic gets hot and melts. Very bad.
* None of the chemicals I tried were effective at bringing out a shine or significantly smoothing the keys. I think mechanical smoothing is better.
* I had a little bit of polishing compound on my felt tool left over, but I never applied more. I don't think it made any difference (it's for polishing metal and is very fine). I personally believe that plain felt would have worked as well but I'm not sure.
Thanks for all your help, guys!