I haven't tried this, but here's a service that claims to pay you to use your Twitter account for tweets:

http://be-a-magpie.com/twitterer

If you have 2000 followers, you'll earn about $50 a month. If interested, check it out and let us know...

Here's another way to directly monetize your account:

http://www.twittad.com/

"Twittad was formed to give Twitter users and advertisers the opportunity to meet for product placement and website promotion on a Twitter user's profile."

Note: You can also buy advertising on Twittad.