Unfortunately, this is not the case.
As it is, I don't bother to use StackOverflow. My questions would be too esoteric for the audience/format, and nearly all of the questions I see are boring, easily answerable with a search of the documentation. The questions would be less boring if I were paid to answer them, and then I'd be more likely to find a few gems to answer, too.
It's doubtful to me that you could appeal to expert users to exchange time for money when it is better leveraged by consulting and entrepreneurship.
This topic comes up quite often on the StackOverflow podcast.
$5-$15 per answer would be reasonable given the limited time involvement.
I seem to have enough free time to blow a fair portion of it commenting on Hacker News.
To understand how powerful this difference can be, this book is an eye-opener (outlined here):
Other than money, how do you prevent an expert-exodus as expert users are deluged with simpleton questions? Amidst a deluge of bad questions, there's little value to remain active, as your own questions can rarely be answered, and users aren't providing interesting questions.
Something else is needed to provide a substitute for that value.
Alternatively, you must prevent the exodus by filtering the kinds of interactions/questions that occur. Mailing lists, for instance, have a barrier to entry to serve as a first-pass filter (the subscription), and then a community to enforce community norms.
Similarly, (most) university professors don't teach for getting rich or just fort the research - they enjoy overseeing and helping the youngest generations of their particular field.
Either way, money is what would entice me to answer questions on the web. Currently I do it for free on IRC, but only because standing community helps ensure that the quality of questions is reasonable on the channels I frequent.
Call me stupid, but I though the SO down vote button was designed to do the message filtering and not Mr Atwood super SO user ID.
There haven't been any mind-blowing awesome gems of answers in there that have caught my eye - mostly pretty mundane things, content-wise, and as a programmer looking for an interesting community, I don't really get that vibe from it much at all.
To me it just seems like a place for kids to go and get their homework done for them by lonely strung out alpha dogs looking to place some authority in the world.
For me, sites like this will never replace the good ol' USENET groups and subsidiary mailing lists. Once again (as is the case with Twitter), a web site springs up to try to capture an audience from the pool of people who are just not competent enough with E-mail to manage it properly and exploit the results ..
Are there allot of simple questions? Yes because there are many people just learning how to do basic things in one language or another. However even in the most basic question answering it can be an worthwhile experience. You can filter out the simple questions and get on to the more advance ones pretty easy.