Among webmasters the most popular ad network type is PPC ads because you get paid for clicks. Google AdSense dominate this market. They are very strict so everyday 100s of publishers get kicked out with or without a reason. Its better not keep all eggs in same basket in case of unexpected ban. So here are other best PPC alternatives you can find around.

Kontera : Also known as ContentLinks which are contextually relevant keywords discovered in real time on a publisher’s web page that are automatically turned into a link to the most relevant and highest paying text ad.

Adbrite : The best alternative ad network for Adsense. Provides Text, Image, intext, popup, popunder, full page ads. Pays through Check and PayPal.

Chitika : Another good ad network. pays by both paypal and checks.

Bitvertiser : pays monthly, either by check, or instantly through PayPal with a minimum of only $10.

YPN : They take only US publishers otherwise they would has been more popular.

Clickshare : A PPC and CPM based Ad network. Pays through PayPal and Check.