I like to use emoticons (probably a bit too much) to make a quick communication look more “friendly” whether email or chat.
🙂 😉 and :] are my favorites
In Lync Comm I like to use the rainbow and big smiley to covey gratitude, the martini glass for thumbs up (implying “great idea!” you deserve a martini,) and the puppy face for confusion. It helps that everyone in my work group has a fun personality and we talked about what each of the little icons might mean and agreed upon a few for certain situations.
I don’t use emoticons with people I don’t know.
Ex: I wouldn’t sent a martini icon to a member of another work group.