It is true that Gmail has many interesting features (Gmail Chat, Labs) that other email services does not provide. But you could not send smilies with your email via Gmail. This was something missing in GMail for quite a long time. Dark days are over. Now you can send Email full of Smilies. Yes quite a lot of smilies. Pictures worth thousand words. So here is the full list of smilies.
Official Gmail Blog: A picture is worth a thousand words
Official Gmail Blog: A picture is worth a thousand words