1. Another Window Session Manager

Close and save open windows. And restore them.
2. Clipboard Indicator

Clipboard Manager extension for Gnome-Shell - Adds a clipboard indicator to the top panel, and caches clipboard history.
3. CPU Power Manager

Manage your CPU's frequency scaling driver.
4. Status Area Horizontal Spacing

Reduce the horizontal spacing between icons in the top-right status area.
5. Recent Items

Adds an icon for recently used items at the top panel
6. Weeks Start on Monday Again...

... or maybe not, and that's why the start day is configurable in the preferences.
7. Vitals

A glimpse into your computer's temperature, voltage, fan speed, memory usage, processor load, system resources, network speed and storage stats. This is a one stop shop to monitor all of your vital sensors.
8. Workspace indicator

Workspace indicator shows the amount of opened workspaces and highlights the current one using unicode characters.
You can use it as an indicator only but widget is clickable. Left button click: move to left, right click: move right. Middle click calls overview.