It’s often useful to know how many external backlinks are pointing to a particular URL. This metric can be used to partly determine a page’s popularity on the Web. A good tool for automating this process is the Backlink Analyzer which uses the Google, MSN, and Yahoo APIs using the "link:" command. The software allows a user to specify sites to ignore in the backlink counts, a useful function since the link: command returns backlinks from external and internal links for all three search engines.
I don’t know for sure if Backlink Analyzer is doing this or not, but for Yahoo and MSN, it is possible to perform a single command to give only external backlinks using a combination of link: and -site: parameters. For example, the following query will show all the pages pointing to my Warrick page for Yahoo and MSN:
Google will not handle the –site: parameter successfully in this query although it does handle it in other types of queries.