WP Plugin: OIOpublisher Ad Manager
It's worth every penny. You should make it all back and more with your first sale.
WP Plugin: WishList Member
WishList Member is a powerful solution for creating an online membership site – all built using WordPress as the core content management system. Now it’s easy to control access to your content, accept payments, manage your members and so much more!
WP Plugin: WP Robot
I have been using WP Robot for a few weeks now and WOW! My traffic is soaring and my Adsense profits have more then doubled. It payed for itself in a few hours. Thanks!