Twitter Monetizing

Does anyone has ever used twitter such as selling ads space or putting some banners or affiliate links, in against to earn money? Does it give a good payoff? If yes somebody has used then how many followers do you have and how much do you earn? Too many question I guess, but I am wondering do people abuse twitter in that sense for getting money?

Twitter is good in direct marketing or getting leads for your business for example. Although it doesn't help that much in SEO, you can still make money easily if you treat it as a marketing tool for your product or online business.