There was a great story/comment thread here a while ago about worn letters and how my o looked like a c. I can`t remember who wrote that particular story; seems they`ve deleted their profile. Always sad.
But now my o is completely worn off, so I can`t even make good c comments...
...and the N and M are nearly gone. My old keyboard was missing several letters--my kids couldn't even use it any more.
I touch-type wicked fast, so the keys could be blank and it wouldn't affect my keyboarding.