What do you use Post-It notes for? I normally use them for things I don’t want to forget (and stick them on to all kinds of surfaces like my handbag or seat of the car) or just as bookmarks.
You’ll find some other ideas in this blog post here. I do like the idea of writing something positive and pinning it on to someone’s desk or door. I’m not sure if I like the idea of sticking them all over the wall though.