There is a program that comes installed with Ubuntu called TomBoy notes. I think the functionality might be a little different from OneNote (I've never used OneNote), but it basically lets you build a notekeeping file and automatically cross references things you type in a note with things you've typed in another note. For example, if you had a note titled "Car repair" and in another note you typed the words "car repair," it would turn those words into a link that, when clicked on, brings up your original note titled "car repair." I would imagine the program is available with other distros as well.
Hope this helps,
Daniel