I responded E, S, N, L, and K. Also the space bar is worn. The E, S, and K are gone. This keyboard is 15 months old.
I don’t believe K is a very high-volume letter, but I do medical transcription and all of my expansions for drugs have a K at the beginning to distinguish them from others.
I do Wheel of Fortune proud…RSTLNE. C, I and O as well, the left Shift key, the right-hand side Enter key and the right-most third of the space bar, which I also use my thumb for.
This is based on shininess, not letter fading.
W, A, S, D, E, F, J, K, L, R, T… I and O, but not so much. And the left shift and space bar. This is based on shine - I replaced a keyboard with several worn-away letters a few months ago. I know J and K are only from resting my fingers there before I start typing. There was actually a little dust on my right shift button.
It’s interesting how S is so common yet T is not all that common to have wear.
I just noticed that only the right side of my space bar is shiny, too! I guess I only hit space with my right thumb! I never knew that before.
None of the keys shows any particular wear.
I have no idea why, but apparently I’m hell on wheels for N and (to a lesser extent) M.
My WoW keyboard doesn’t show any wear. My old laptop’s N is completely gone. This laptop’s N is half-missing. The full-size keyboard I’m using right now has the N and M completely blurred out; the N didn’t last 48 hours. Oh, and I’m definitely a right-thumb spacer.
Admit it, you’re just using this poll to try and figure out people’s passwords, aren’t you?
I doubt that would work. The letters in my password aren’t especially worn on my keyboard.
You forgot to ask about function keys. My F3, F4, and F10 are getting shiny compared to the others. Why yes, I’m in the mainframe a lot… I’m actually surprised F8 isn’t worn more as it also sees a lot of poking throughout the day.
“A” is worn down to just the left bar. The right side is almost gone and the cross-bar is gone. The bottom half of “S” is gone.
This is all on a roughly 15 year old IBM-branded keyboard.
Q,W,E,S - Thank you WoW. I changed a couple on my key mapping which is why I have the Q and E instead of the A and D.
L and M
No idea why - neither letter is in my name or my username. Maybe I LOL a lot?
The right side of my spacebar is shiny, and there are shiny palm-sized wear spots under each side of the spacebar.
The spacebar.
My keyboard is ~1985 vintage (IBM Model M) but no key sshow wear. Just dirt!
M is totally gone. K, L, and N are mostly gone. C is about half there, half not. Most other letters are unscathed.
You could grind 1/8" off those keytops and still read the letters as they’re double-shot molded, unlike pretty much everything else on the planet that’s just screen-printed onto the caps.
My keyboard just got cooler! 
While a couple of the letters are worn, it’s the left <shift>, the space bar, and 0 on my 10 key that have the most wear.
I entered all of the letters that were at least half worn away. There were eleven of them. Four are completely gone. V is nearly gone, and I’m guessing that’s only true because of Ctrl-V for pasting.
I’ll look again when I get home, but my work computer has almost completely lost E, N and M. The H key is at about 55%. Everything else is largely intact. I’ve had my work computer keyboard for probably about four years.
My hp Pavilion dv7-4065dx Entertainment Notebook with 17" screen is only 2 weeks old, along with MS Office 2010, so there’s no wear yet, except for the hp & Windows HELLp buttons (if there was one).