unique download links that limit times can be used

Hello:

I am looking for a way to do this; either through a plugin; or some php code; or through a third party service. What I want to do is be able to send people a unique download link that then will only work one time. We do not want to use the wp-mailer. Also we have a plugin that does it (our shopping cart plugin “cart66” but we do not want to do this with all of the “cart functionality”. Just something that will send the link the way I have described. Can anyone help? Thanks!