One day, well on a not so busy one, I will try and make my own Indicators for my Linux machine. Indicators in Unity Environment are a quick way to access the information or present info to the user. Things that take time like video encoding/code compiling can have a very intuitive interface with the taskbar icon which when clicked shows the progress.
For more info check this link.
Although good, but there is too little documentation to get you started. After a lot of explorations around the web, i was able to put together this template for building app indicators that exit gracefully and have an on click event that updates the menu dynamically. I had made it to essentially track some parameters on a remote system. So, whenever i clicked, it fetched data and presented it. A bit better than running a parallel thread even when data is not required by the user.
The basic code is here in the git repo.