Microsoft OneNote is an excellent note management tool. I am addicted to it! Though, it is not a freeware. If you are looking for freeware alternatives of Microsoft OneNote, I would strongly recommend Evernote, Google Notebook and Zoho Notebook.
Evernote has a desktop client with limited sync option for free users. Evernote also provides a brilliant clipping add-on for Firefox. I was looking for a similar tool for OneNote, and finally I got this add-on.
Clip to OneNote is an unofficial tool by an independent developer Madharasan, and capable of sending text and images to OneNote from Firefox with just a single click.
How To Use Clip to OneNote?
Install the add-on, and restart the browser. Users need to provide the path to onenote.exe on their system. To setup this, refer add-on’s page @ AMO. Now, you can use the option “Clip to OneNote” to send text and images to OneNote. This option is available at three places: in right click context menu, in the edit menu, on toolbar (by default it is not visible on toolbar).

All text and images hence clipped to OneNote will be saved as a new page in unfiled notes section. You can drag items from the unfiled notes and drop to any notebook later. :)
A must have add-on for OneNote users. :)
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This add-on was working fine with MS OneNote 2007, but breaking with the Office 2010. Sad, but developers of this tool should fix this