I still don’t understand why Gmail has no emoticon feature, still!! Gmail stands high among its peers in many ways. But Yahoo looks colorful for its set of emoticons and this particular feature grabs and retains many users. The more I thought of it, the more I wanted to search for any third party tools to power this feature into Gmail system.
I found an awesome tool to achieve this. A Greasemonkey script. Yes, as you would have guessed by now, it works only with Firefox. Never mind. Cheer up.
for script and more on this post comments.