With GumNotes you can create text notes which can be attached to any window like a FireFox tab that contains a specific string like "mystring" and or another window that contains "another string" and automatically your associated note pops up if this tab or window is active.
You can even connect your text note with a local zip file or pdf file that is associated with a specific tab or window for quick access.
It's freeware and you can sync your texts with SimpleNote.
Download it here: http://www.gumnotes....nload-gumnotes/
Integrates very nicely in your daily work flows - try it out. Shortcut to attach a text to a window is Control+R (after it is loaded).