Facebook recently added the ability to target advertisements by Topic, as detailed in its new Interests Targeting guide (.PDF). Rather than targeting users that Like a specific Page, advertisers can simultaneously target all users who Like any variation of a word or phrase. For example, rather than just targeting fans of Lady Gaga, by selecting the #Lady Gaga Topic, an ad will also be shown to fans of any unofficial Pages for the musician, such as “I ♥ Lady Gaga”.