John's Background Switcher - Switch backgrounds to trending imgur, reddit, tumblr threads
iStat Menus - "An advanced Mac system monitor for your menubar."
Wallcat - Enjoy a new, beautiful wallpaper, every day.
iStatistica Pro - System monitor. Reinvented. 💻 🖥
Splashy - Breathtaking, auto changing wallpaper app for macOS, Windows, Linux, iOS & Android
Stats - Simple macOS system monitor in your menu bar.