Very interesting idea though I think that would be hard to do since there are a limited number of 16 digit numbers and if people could use a program to generate an infinite number (say, one for each transaction that is temporary so it can never be stolen) we would run out.
However, I do think that some combination of "paying by email" and some email programming could get you something interesting.
In any case, this idea should get more people thinking about the possibilities.
