For some assignments, I have cut Post-Its into strips and written the words "START" and "STOP" near the top. Emperor can use these as tabs in his book. In our science book, this is especially useful as the assignments often begin and end midway on a page. I can tuck the sticky note out sideways and he knows right where to begin and end.
I also keep a stack of Post-Its by my computer. If there is a particularly blinky- or boobie-type ad on the sides of the article I'm viewing, I just pop the note on the screen and viola! It's gone.
Yes, I wrote "viola!" to be funny. "Wahh-lah" is also a favourite. "Your" welcome. :p