Adding note-taking features to Firefox is not a new idea, and there are a few extensions out there that allow you to scribble notes right from within the browser. So which one to choose? If you need a tool which a) makes it extremely easy to enter notes, b) searches the existing notes, and c) synchronizes notes between multiple machines, then you should consider list.it. To install the extension, you have to sign up for a lits.it account (you need it to synchronize notes).

Once installed, the extension adds a Note icon to the status bar. Click on it, and you can quickly enter or paste text in the opened text field. To view your notes, press the appropriate keyboard shortcut (by default, it's Ctrl+Shift+F). This opens the list.it sidebar, where you can manage and search notes. To be able to synchronize notes, you can configure synchronization settings first. To do this, click the Options button in the list.it sidebar, or choose Tools -> Add-ons and press the Preferences button next to the list.it extension. In the opened Option dialog window, tick the Support Synchronization check box, enter the email and password you specified during the signup process, and press the Accept button. Now you can sync your notes by pressing the Synchronize button in the sidebar.