I was just thinking that because this is a math site and numbers are just a bit important to math that maybe the person who asks the $1$,$000$,$000$th question or even the $800$,$000$th (or whatever interval we could decide on) could be given a small reward, such as a rep bonus, nothing huge, just as a kind of reward? Maybe we could require it to be a well-recieved question as well, so people wouldn't just spam random questions in order to get themselves the rep bonus (although I doubt anyone would do that.)
No, we shouldn't do this because there doesn't seem to be any good reason to.
What would be the purpose of such a thing? It would be given out roughly randomly, which seemingly defeats the point of reputation which is to measure the quality of a user's contributions. Can you give a reason why this would be a good thing to do? Generally speaking, changes to existing systems should be done for a reason, not just for fun. I could understand a site-wide thing for the occasion of 1 million questions, such as "double reputation week" but I don't see any good reason to reward whoever happens to ask the millionth question, and it seems like a potentially divisive act.