So many women at work wear off their letters within 1-2 years because they have long fingernails and they use them to type. Then they bitch when I tell them I won't replace their keyboards until they cut their nails.
you could cover each key in clear nail polish - nab some from you g/f / wife / tranvestite.
It should create a thin covering to protect the key but probably isnt that hard wearing and would need topping up quite often. Also a bit tricky as you dont want to get it under the keys!!