InstaBreak - Break blocks instant! Version: v1.0 Features: Break blocks instant. Download InstaBreak! Source is inside the jar file. How to use: First use the command "/instabreak" (or "/ib") for enabling InstaBreak (use the command again to disable it). Then you can break blocks with one single left mouse click. Permissions: Give the player you want this permissions. Code: instabreak Known bugs: None. Changelog: Version 1.0 Release.
There's already a plugin with this exact name and almost exact subject: http://forums.bukkit.org/threads/edit-instabreak-v1-9-break-blocks-instantly-860.11494/