Arguably, but not really, the most popular emulators on the Android Market have been yanked by Google. The *oid line, developed by Yongzh, seems to have finally rubbed Google, or some console developers the wrong way.

Engadget has noted that Mr. Zhang has moved his line of emulators to the SlideME store where they will be free for the time being so users who purchased the apps in the Market will continue to receive updates for the time being.
SOURCE: Android Market's most popular emulators disappear without a trace (update) -- Engadget
SOURCE: Android Market's most popular emulators disappear without a trace (update) -- Engadget