One thing that you can send to your affiliates are email swipe messages to their email in box that already contain their affiliate links. Let them know it is time to send that message or one similar to their list. This will help remind affiliates who have signed up to promote that it is time to send something to their lists.
It also makes it easier for the affiliate to take immediate action.
You don't have to confine it to only email swipes...
It could be a blog post, article, tweet or classified ad that can be used for PPC.
Let these tools promote the problems and how your product helps to solve the problems. The easier you can make it for affiliates to promote your product, the more the affiliates will respond by promoting. Don't always count on affiliates returning to your affiliate center to get the latest promotional tools you supply.
Eric Conklin 
