OctoPrint has various plugins that can enhance its functionality and improve the user experience. While personal preferences may vary, here is a list of some famous and valuable free plugins:

1. OctoLapse: This plugin helps you create high-quality, stabilized time-lapse videos of your 3D prints. It offers advanced features like print head movement synchronization and customizable settings for time-lapse capture.

2. Bed Visualizer: This plugin allows you to visualize the bed leveling data from your printer to help identify any irregularities or issues with the bed surface. It can be beneficial if your printer supports automatic bed leveling.

3. DisplayLayerProgress: This plugin shows the current layer and total layer count in the OctoPrint interface, giving you a better sense of the print progress.

4. OctoPrint-Telegram: This plugin integrates OctoPrint with the Telegram messaging app, allowing you to receive notifications about your print progress, send commands, and even receive images of your prints directly on your phone.

5. Themeify: This plugin lets you customize the appearance of the OctoPrint interface with different themes and styles, making it more visually appealing and personalized.

6. Preheat Button: This simple plugin adds a preheat button to the OctoPrint interface, allowing you to quickly preheat your printer to the temperatures specified in your slicer settings.

7. FileManager: FileManager enhances the built-in file management capabilities of OctoPrint by offering features like folder organization, bulk actions, and file previews.

8. AutomaticShutdown: This plugin can automatically turn off your 3D printer after a print has been completed, which can help save energy and reduce wear on your printer components.

9. OctoPrint-PSUControl: This plugin allows you to control the power supply of your 3D printer remotely, enabling you to turn the printer on and off directly from the OctoPrint interface.

10. OctoPrint-Dashboard: This plugin adds a customizable dashboard to OctoPrint, displaying information like printer status, print progress, and temperatures in a visually appealing and easy-to-read format.

Note: new plugins are constantly being developed, and it's a good idea to explore the OctoPrint Plugin Repository for the latest additions and updates. Also, remember to check the plugin's compatibility with your specific printer and OctoPrint version before installation.