WidgetBucks
WidgetBucks are one of the latest PPC network that we’ve been using - and so far the results have been impressive. Their ads look much nicer than many other PPC product ads, and are very easy to blend into your site - you can even use WidgetBucks ads along side AdSense. Minimum payout is $50, and they pay publishers by check or PayPal.
Recommended.
» More info here

Chitika
Chitika is one of the best Pay Per Click programs around if you run a technology or gadget blog, or if your site is about a specific product. Chitika have a huge range of ads, and their code can easily be made “smart” using php to drop in keywords depending on your page title, or blog post title. They also offer payments by PayPal.
Recommended.
» More info here

Google AdSense
Google are the kings of PPC - and offer some of the most targeted and ‘clickable’ text and banner ads of all the PPC programs. They have a strict set of rules that publishers must follow, so make sure you read their TOS thoroughly before signing up - if you lose your AdSense account for breaking the TOS, there’s next to no chance of ever getting back in.
More info here