Have you tried ADster, and what do you think about it?
I have mixed feelings, I think it is good for some people...and you might want to check it out and see if it's a good thing for you.

It is not pay per click advertising, you pay for a block of time on the sites of your choice. You can browse their network of advertisers. You can join the network of advertisers or you can buy advertising.
They have added pay per click just recently though.
I tried the pay per click, but most of the sites weren't really my target market at all.

www.adster.com and you can see the ADster panel on my blog (right hand side) http://www.darligraphy.blogspot.com/ ... when you look at it, click on the link in the bottom of the box that reads "Advertise Here" and you will see more about it in action. It is an interesting concept...you see it on someone's site that you think it a good fit with what you advertise...you can see how many clicks that site gets per day, etc. You can pay what they ask for the advertising, or you can make offers (I have found that most will accept even really low offers, if what you sell is a nice match with their site).

You can add ADster to your site or blog for free. They will automatically put pay per click advertisers in it. My blog doesn't have the one with the pay per click advertisers in it, because some of the advertisers were products my family-oriented clientele wouldn't appreciate ("Pimp your Cell" and "Cheat at Poker" are two memorable ones that don't fit with my client base).

One thing they are a big winner in my book for is communication.
I had some questions, emailed them, and they emailed me right away.
I didn't have time to get back to them that day, and the CEO called me! I was really impressed by their customer service.
So this is a company to watch I think.