For checking Google back links you can use the operator "link:url" But now you can also use Google Webmaster tool to view a much larger sample of links to pages on your site that Google found on the web. Unlike the link: operator, this data is much more comprehensive and can be classified, filtered, and downloaded. All you need to do is verify site ownership to see this information.
Besides , you can use yahoo site explorer to see yahoo backlink. With SEO quake you can even see Bing back links.