A few of the keys on my Kindle 3 (“Kindle Keyboard”) had started to fade away with use. Not that they were all that visible to start with. I’d describe them as matte, off-white on a medium gray background. Recently, I discovered that a vinyl skin could be purchased which covers the keys on the Kindle, and features far more readable keyboard lettering. You can see a before and after comparison in the photos below.
These skins are made by Invisible Defenders and sold at Decalrus.com. Specifically, the Kindle 3 skins covering the keyboard area are called “Kindle 3_NOKEY” skins and they have a selection of over 600 styles. For $11 USD, I think they can make a tremendous difference for reading the keys and offer some protection as well. Or if you would prefer to buy one from amazon.com (from $11.95 and up) search their site for “Kindle 3 nokey”. If you don’t like the shiny vinyl look they also have some with a matte finish.
Update: To clarify pricing: Decalrus.com skins are $11.00 + ($3.00 for matte option) + $3.00 shipping. Amazon.com skins sell for $11.95 +($1.00 for matte option) + $4.99 shipping. If you can’t get free shipping, then both shiny and matte skins are cheaper direct from decalrus.com.