Here are some ad networks that have Domain-Targeted/ PPV Traffic
PropelMedia.com
RTXplatform.com
SelfAdvertiser.com
Zeropark.com
PPV are not as prevelant as they once. Internet Marketing is a forever changing industry. Ad networks go out of business, traffic generating methods become obsolete. So the best thing you can do in this industry is to constantly be open to learning and trying new things, dont become to complacent and keep a great network of knowledgeable people in order to help keep you update with whatever is currently working in the space.