Depends on your followers and what they want. I know people in the food industry (chefs, owners, etc) who do good on twitter when it comes to tweeting out about the latest kitchen gadget, etc. Myself, I drive traffic to my blogs and sites via twitter. For money on twitter, it is again affiliate links to items I believe my followers may purchase. Do okay on some amazon items, and learned other items are not going to sell to my followers.
Making money with Twitter got harder these days. Mostly all of the members that uses Twitter is for sending traffic to their pages and hopefully those visits will turn into buyers/subscribers.
I'm currently making $120 daily with twitter alone with outsourcing. I read this article over here: http://iblackhatseo.com/?p=7456 There are plenty of options to monetize it and you need to tweak it. Find your best way and then just rinse and repeat.