Plenty. You need to get on more sites with more members. Long time shared sites like Digg, Xomba and She Told Me will also share revenue. They also have no objection to your posting links to your hubs. Red Gage is an interesting and new up and comer.
You can find plenty of others in the Addthis drop down menu. Join a few you feel comfortable with. I especially like Digg and Xomba, just because they're easy and have members who read. I would suggest, in addition to Twitter, you post everything to Facebook and ask your friends to share with their friends. You end up with new contacts and, hopefully, many back links.
Finally, and most importantly, get involved in the sites you post to. Establish some friends and comment thoughtfully on their links and in forums. Xomba even as a chat feature. All these things help others get to know and like you. If you are writing good, original material that others like to read, you'll do fine. But be patient too. You can't build a presence overnight. Creating an ad and affiliate based business takes time, and there are few shortcuts.