Related to ^^ ^.^ ^-^ etc, but it adds a head shape and right-side curve of the mouth.
In most cases, it's simply an 'emoticon' symbolizing extreme joy, or an innocent face.
It's also used to annoy jerks by showing that you simply don't care what they say about you.
Person 1: I love diet pepsi (^^,)
Person 2: Shutup homo.
Person 1: Hey hey, don't be hatin' ^^
Person 2: Wow, you're annoying.
Person 1: (^^,)