System indicators is a lightweight monitoring tool that resides on OS X menubar. It provides a glimpse of the current system status including CPU, RAM, disks, network and GPU(experimental).
The app is fully sandboxed and runs in user space to securely access system APIs. No installation process. No sudo previlege is required. You can choose which type of indicators to be put on the menubar with customized color and width. The app has one single process with minimal system footprint. No additional daemon process is running in the background.