I'm sure I'm not alone in that I find linkdomain: searches on Yahoo much more useful than link: searches on Google. However, the results return seem to show up an unlimited number of results per domain name (the domains that actually do the linking). Does anyone know if a tool exists that will run a linkdomain search on Yahoo and count the number of unique domain names in thr results? It might be a little heavy with regards to processing power / bandwidth required for sites with many millions of backlinks, but if it was perhaps limited to a few hundred it might be a nice idea.
If you can do linkdomain: with their API it would be quite easy to accomplish. Extract all the root domains from the linking URLs, then do a DISTINCT query on them.
Problem is you are going to be limited only to the first 1,000 results since Yahoo doesn't show anything beyond that (on the website or API).