For times where :-) just doesn't quite convey the message.
Buzz on the Web is that Nokia has filed a patent for light messaging. Unless you text that you're mad or happy, chances are that you'd have to append a :-) or :- ( to set the tone of the message at some point. This helps the receiving party know how you were feeling when you sent the text.
Just think of these subtle SMS emoticons in the form of colored lighting and you'll have an idea of what the Finns are up to. It works like this. Before you hit Send, you get an option to select a color, and depending on your mood or the urgency of the SMS, you can select red for high priority (or fuming mad) or blue for sad. The encoded color will then be displayed either via LEDs or on the keypad of the receiver's phone.
Sounds like a feasible idea--if a little gimmicky. I'm just not sure how I can deal with a disco phone.