There was some fuss made over a new toaster about a year ago, I seem to recall. It had an optical sensor that could "see" how brown your toast was.

Ah, here it is:
http://www.engadget.com/entry/4607362272658138/

Regarding thick slices of toast - that feature is known as "wide technology" or "bagel technology". And I thought that software marketeers were bad!