Pay-per-action programs are also referred to as "affiliate programs" as publishers advertise products and, in return, receive a revenue-share of the purchase price when a sale is made.  As mentioned, website owners are compensated only when there is some type of "action" taken on the part of visitors.  Most of the time, that action will be the purchase of a product or service.  Although it is harder to sell products or services, each time a sale is concluded, the revenue-share is much more significant than for other types of programs.

For publishers, one main factor to consider when deciding what pay-per-action program to participate in is how receptive visitors will be.  Going with brand name products is the easiest way to generate revenue since you can rely on brand name recognition.

For advertisers, this type of advertising is often preferred as they only pay when a sale is concluded.  Note that most pay-per-action sites allow advertisers to choose who to admit into their programs.  This allows advertisers to screen out websites they don't want to be associated with.

The main pay-per-action programs are:

• Commission Junction
• Azoogle
• ClickBank
• LinkShare
• Share Results
• Amazon
• Chitika
• ClickBooth
• MarketLeverage
• Auction Ads

In order to make the most out of these programs, you need to:

• Attract a targeted audience by optimizing your search engine results to specific keywords.
• Position the ads to blend with your content so that visitors do not see them necessarily as ads.
• Position the ads as adding to the content of your site by having targeted ads.
• Offer relevant and good-quality content so that you build your credibility.  If visitors see your site as credible, they will also see your recommendations as such.
• Offer reviews and comparative tables and charts to help your visitors choose the products that best fit their needs.
• Cloak affiliate links on your site if possible.

You need to sell products or services and you want to attract as many publishers as possible to spread your message?  Following are some tips:

• Simplify the process for publishers in terms of explaining what your product is about.
• Target the main websites that deal with your product by sending out emails to those sites and trying to convince them one at a time.
• Offer a wide range of banners and text links.
• Enter into credible programs such as Commission Junction, which has a huge publisher base.
• Choose your publishers if you don't want your brand to be associated with a bad neighborhood.
• Offer incentives that will reward publishers for their efforts.  Unless you recognize that you need them and are willing to give them a decent share of the pie, they won't work for you.
• Give out promotional coupons and updates to your publishers to motivate them and help them increase their sales.
• Ask for feedback from your publishers to have their perspective on what works best.
• Don't view the money that you pay to publishers as a waste.  You should want them to do well because if they do well, you will do even better.

Commission Junction

Commission Junction offers the biggest pay-per-action programs with advertisers such as Yahoo!, Monster, Ebay, and so forth.  It has an accurate tracking system to ensure that publishers are compensated for the leads they generate.  For businesses looking to sell products/ services online, Commission Junction has a huge base of publishers on which you can rely. 

Azoogle

Azoogle is another major player online, but has "second-tier" advertisers selling products/ services such as ringtones, online dating, etc.  Azoogle differentiates itself in terms of the ad sizes they have, which are much bigger and prominent.  Azoogle provides good support to publishers by associating with each publisher an affiliate manager.

ClickBank

ClickBank deals mainly with electronic products sold online such as ebooks and softwares.  It differentiates itself from other pay-per-action programs because customers pay them directly.  That's how they track sales that are made.

LinkShare and Share Results

LinkShare and ShareResults are relatively similar to Commission Junction because they have big name advertisers.  The main difference is that they are much smaller than Commission Junction and, accordingly, have a smaller advertiser and publisher base.

Amazon

Amazon manages its own affiliate program instead of contracting that out to intermediaries.

Auction Ads

Auction Ads displays relevant (content-targeted) live eBay auctions in banner format.