Contextual link is a nice addition made into Drupal 7 to favor usability. It offers, quick links to pages performing administrative operations. By default it is available for core block and node teaser view. But designed to be made extendable for other items too - Views, panels, and so.
Custom contextual link (aka ccl) module is the best choice for adding custom link items.
But I have faced some problems in ccl module while adding a custom contextual link for a block.