Yes, it is possible for you to advertise on your own Web site, to drive traffic to that same Web site. If you both are a publisher and an advertiser in a contextual ad program like Yahoo Publisher Network / Yahoo Search Marketing or Google AdSense / Google AdWords, you can run your own ads on your own site. That is the topic of a thread at WebmasterWorld. But don't fret it, you can block yourself from showing your own ads on your own sites. This is important to keep in mind, when running both the publisher side and advertiser side of things.
Forum discussion at WebmasterWorld.