Aaron is keeping himself at the front of the pack and investing some money and time to give the community a bunch of handy free tools. If he keeps this up I may have to see if they can add a philanthropist of the year award to the SEW awards.
This nifty little tool checks backlinks from Yahoo by domain... listing each referring domain once and counting the number of total links through various pages that link to your domain.
You can then filter by these duplicates and grow out the numbers.
It becomes a handy tool to see if you are getting too many links from a given site. You could see who links to your competitors or also what sites have links for both you and your competitors.
It is a hosted solution and offers a CVS download of the information. Something every SEO/SEM company should be using to provide insights to your customers.
Go try it out at Link Harvester