I read an uncounted number of pages everyday. In the stack of books and print-outs I try to digest, I usually leave some traces in form of sticky notes. Sometimes I leave so many that when I open such a book again, I can hear the wind go through the attached notes like through the branches of an autumn tree (I an aware that I do have a very vivid imagination).
On a recent journey to Stockholm, I found a set of sticky notes from 601street, a Korean company, that enhances the forest impression visually: The set offers three different sizes of notes featuring in total 20 types of leafs printed in either brown, yellow or green. Check out their cheerful designs on their website.