I learned this concept years ago from Dottie Walters (check out her Magnificent Marketing Symposium which is coming up in just a few weeks)http://www.speakandgrowrich.com/s_2003_mm_tom.aspx
Smart speakers attempt to maximize the amount of money they make at each speaking engagement. Contract marketing is one way to do it.
The idea is to put a mention of other products or services in your contract / agreement after you have landed the speaking engagement.
It could go something like this, "Additional learning materials available to match this presentation.
"You would put this in a prominent place in your agreement.
Many organizations have budgets to buy educational materials for their members or employees. Why shouldn't they buy them from you?
You might say, "Tom, why don't you just discuss additional product sales up front with the meeting planner and put the deal right in your contract?"
The reason is that the meeting planner doesn't always know how much budget that is available for this until all the top priorities are under contract. When the final review of the contracts occurs your reminder in your contract could land a very big deal doubling or tripling the value of your engagement.