Yahoo! Web Analytics automatically tracks your Exit Links, once you have deployed the tracking code on all the pages of your website. You can find reports on your Exit Links under Reports > Navigation > Exits.
These reports will help you identify which links drive away traffic from your web site. You might want to negotiate advertising or link exchange agreements with the owner of websites that receive significant traffic from you.
Exit Link = A Yahoo! Web Analytics term used for a clicked link that is not within the domain structure of your tracked website.