For publicly available link data, the link: operator works on all three major search engines - Google, Yahoo and Bing (but not Ask). Each one can show you a slightly different sample, but they are all limited to under 1000 links. For sites with total links under 1000, Yahoo seems to be the most complete, but sometimes they get out of date.
There are also private sources of link data that you can pay for, but we're not going to mention them here - the Google Forum Charter [webmasterworld.com] asks us not to mention specific SEO tools and that's especially so when it comes to tools for profit. It's not hard to turn up backlink tools through search.