No, not their search engines. Their Groups!
There are thousands of groups organized around specific topics trading messages and information. There are more groups listed then you could ever intelligently promote. Review, select, then promote and take action.
When someone is in a group you already know they have an interest in a topic. Now it is just a matter of getting them into your own list, or getting offers in front of them.
There is nothing that stops you from starting your own groups. Create a Yahoo Group and send messages to its members that include offers.