You can earn money from your twitter account in many ways.Tweet affiliate links,send traffic to your own site,use Twitter Advertising Networks.Twitter Advertising Networks are certainly a very good way to monetize your twitter account.Here is a list of sites that can help you earn money with your twitter account.

adClause:

adClause is one of the first Twitter Advertising Networks.As a twitter user you’ll get paid to publish advertiser’s tweets.The more followers you have the more money you can earn.To earn money with adClause all you need is a twitter account and a PayPal account.

As a publisher you have complete control to choose the ads that you want to show in your timeline.You can disapprove ads that are not related to your niche or you know your followers may not like.

You get paid when your earning reach $25.

twtMob:

twtMob pay you to tweet their contents like comedy sketches,music videos, movie trailers etc.You’ll be offered campaigns according to your preferences.You are free to select or deny the campaign.Once you send the campaign tweet you earn money.

TwitPub :

It’s a new concept.It’s a marketplace for selling and buying premium tweets.Twitterpublishers can sell premium tweets to the potential buyers.Premium tweets are high quality niche specific tweets e.g. events, news, horoscopes, jokes, stock tips,feng sui, politics, financials etc.
You need to set Twitter account to private (or protect your updates so it’s not publicly visible) from your Twitter settings.Now,signup for TwitPub and their system will automatically approve subscriptions to your Premium Tweets.You can set the price you want charge as subscription! fee.

TwitPub gives you 80% of the subscription fee earned.Once reached the minimumearning for payout they pay via PayPal or a check.

Betweeted:

Betweeted is another twitter pay per click network.Once you sign up with them you can browse through the advertising links available to be posted.Now, select one that is of high pay per click and interests you.Post that link to your twitter timeline.Whenever some your followers click on that link you get paid.

Twittad:

Twittad is a twitter monetization network.They offer two ways to monetize your twitteraccount-

1.Post Twitter Account for Advertisers to Sponsor,where you can select the duration and price of the sponsorship,and when an advertiser offers you sponsorship and you accept that,they will tweet ads into your timeline using the twitter API.

2.Opt-In to Advertiser Campaign,where you can search for available advertiser campaigns based on your interest and earn money for tweeting that.