Internet Friends од Mike Singleton

When on the same webpage with another user, you will see each other's cursors and chat messages.

To chat, use the 'Open Chat' key combo in the Internet Friends settings ('Ctrl + Shift + Enter' by default). Type your message and press Enter to send the chat message. Click on the background of the webpage to close the chat input.

If you change the key combo to a combination without Ctrl, Shift or Alt, the background of the webpage must be selected before using the key combo.