The WP Amazon Associate plugin comes built in with an optional Amazon Associate Filter. If enabled this filter will parse all page/post content and comments for all static amazon product links and convert the associate tag to your defined value in the WPAA plugin that matches the links locale. This feature is built to be non obtrusive and as such will not rewrite the link, instead it determines if the link is tagged and if not will append it to the url or if present will replace the tag leaving the rest of the link untouched.
For example lets assume a person left a comment on your blog with the following link:
As can be seen the link is tagged with their associate id sample-20. The Amazon Associate Filter would replace this with your associate id (yourID-20) changing the link to :
Download the latest version of the WPAA plugin to take advantage of this feature today.