Yahoo Messenger is one of the oldest and popular messenger. I have been using Yahoo messenger from years. Yahoo messengers come with default emoticons which are very useful. Just to let you know yahoo messenger is full of hidden emoticons which you can use to spice your chat experience.
Here is a view of Default yahoo messenger emoticons which you can use :
Now here is a screenshot of hidden yahoo emoticons which you can to enhance your Yahoo chat experience:
Initially you might need to take help of the chart but later on you can use shortcuts to quickly add emoticons.
You can find the full list of hidden emoticons here.
Do let us know which messenger you are using more? Is it, Yahoo or MSN?