My husband does it like this:

:-)

I used to do it like this:

:)

But now do it like this:

^_^

And recently, I got this cute incarnation of it 
in my inbox from a Japanese native (if it doesn't 
show, try switching to shift-JIS encoding):

(��_��)

YES! It is. . . THE SMILIE! The one and only way 
for people on the web to know that you're really 
kidding about something. The ingenious character 
sequence that has stopped and/or prevented many a 
flamewar!

But ever wonder where it all started? Or who the 
heck thought up this staple of online life? 
Apparently the Smilie is just about to turn 20 
years old! Take a look at the link above, which 
my husband just ran into. . .

And then show off some SMILES in the honor of the 
Smilie's birthday! ^_^

Many Sharp Smiles,
--Drac