Please list here ideas for potential plugins. Do not include lengthy discussion about why/how the plugin should work, but link instead to an issue where this would have been discussed.
By listing these ideas here, we can keep the issues list a bit more clean, and have a centralized place where people wanting to contribute can find potential enhancement ideas.
Also have a look at https://github.com/shaarli/Shaarli/issues/14 for other suggestions.

• Mozilla Social API integration
  
• File sharing/Upload service integration
  
• Publish to social media services (twitter, facebook, ...)
  
• Comment system
  
• Syntax highlighting support
  
• Piwik tracking code integration
  
• Pingback support