The link: directive in Google will find all pages which link to a given site. E.g. putting this in Google:
link:stackexchange.com
returns a bunch of sites linking to Stack Exchange.
Is there an equivalent directive in Bing and/or Yahoo?
The link: directive in Google will find all pages which link to a given site. E.g. putting this in Google:
link:stackexchange.com
returns a bunch of sites linking to Stack Exchange.
Is there an equivalent directive in Bing and/or Yahoo?
I do not believe that Bing has one.
See this, https://superuser.com/questions/19164/does-bing-have-advanced-search-operators for more general info on Bings options and how to find them.
Specifically, this page from Bing, http://onlinehelp.microsoft.com/en-us/bing/ff808421.aspx covers their search options.
Finally, Yahoo probably is a duplicate of Bing since all of their searches comes from the Bing engine.
Bing doesn't appear to recognise the link: operator. However you can see links pointing to your site through their webmaster tools (same in Google).
Yahoo, on the other hand, redirects all link: queries to its neat Site Explorer tool, which is the most comprehensive for domains you do not own. I don't know how long this will stay online for now that Bing runs their search results.
Another useful source is Open Site Explorer by SEOmoz. Their index is small by comparison but you can usually see the most important links.
Incidentally, although Google does technically support link:, they never show enough links to be remotely useful.