If you are looking to better monitor what is happening on your Mac, you can try Sloth : this utility displays all open files and sockets (network connectors) used by processes running on your system. This will allow you to easily check which application is using what.
The interface is as simple as possible, with an upper bar in which you choose the elements to display and a lower one offering different actions (display in the Finder, stop a process, etc.). Sloth is actually a graphical equivalent of the function lsof with different filters making it easy to navigate.
The app offers among other things to visualize the sockets and the links established between the processes (pipes), but also to display information in a separate window. You can sort your processes by name, user ID, process type, package ID, etc.
The program is open source and was coded by developer Sveinbjorn Thordarson. You can download it on his site or since the Github page of the project. Only downside: the interface is in English.
