A blatant plug...

My good friend Chris Reynolds does custom comb work and tuning on harmonicas. Here is his website. The guy does excellent work, if you are a player or collector I would recommend picking one up. Here are a couple of pics.Chris does extensive filing, giving the harp a custom touch.
You can get whatever you want engraved on the harp for an additional charge.

It's pretty cool, I talk to Chris on a regular basis, and he has some bitchin ideas coming up. Plans for working with damascus steel and titanium are in the works.