Since yahoo site explorer is now dead I have been looking for alternative ways to profile backlinks.
to check your own backlinks and the backlinks of your competitors
http://blekko.com search for “yoursite.com /seo” note the space between yoursite.com and /seo
http://blekko.com search for “yoursite.com /domainlinks” note the space between yoursite.com and /domainlinks
http://www.opensiteexplorer.org/
for checking the backlinks to your own site:
http://www.google.com/webmastertools > Your site on the web > Links to your site
http://www.bing.com/webmaster > index summary > incoming links