Using drupal 7 block from another website luckily on same server
Here's a Shared Blocks module for that purpose written by well known drupal community members.


  Features:
  
  
  Allows publishing and subscribing of Drupal blocks
  Changes to published blocks are updated on sites with subscription blocks
  Published blocks provides a JSON endpoint at sharedblocks/{module}/{delta}
  Block subscriptions are updated on cron with an adjustable refresh interval