Banner Coops
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A banner ad co-op is a membership program that will display your banner on multiple traffic sources by bulk buying ad spaces and or by rewarding members with ad impressions in exchange for displaying the basnners of other members, The term is often interchangeable with 'banner exchange', with many services providing and identifying as both .

Banner Creation
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What an effective banner should look like?
A good banner is one that works – irrespective of message, color combination or graphic. If it motivates readers to click you have success! To measure a successful ad one only has to look at the number of click through rates (CTR) it generates.
Create a message that will entice action. Do not use the company name, what you are selling as you want to heighten their curiosity as to what is behind the box. If you do use your brand name you run the risk of them assuming they know your brand, therefore they won’t be interested.
The message needs to be short, immediately understood and call them to action by using any of these keywords e.g. free, save, % off, new, limited offer, sale etc.
Call to Action - Have a clear and immediate message that will create a sense of urgency. Limited offer means that if they don’t act now they will be losing out. Human nature finds this hard to resist. Submit buttons are an example that we are all familiar with, even though it is not a banner. A successful banner should shout out what the action is you want the reader to take. 

Banner Exchanges
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An Internet advertising network that swaps banner ads among its members. Each time a member site displays an ad from the network, it receives some amount of credit that is used to display its own banner in the network. PCMag

Banner Rotators
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A Banner rotator is a special type of banner that rotates several banners. ... The Probability of each sub-banner can be defined by the ranking of the banner. Banners with higher ranking will be displayed in the rotator more often than banners with lower ranking. PostAffiliatePro

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