Personally, I prefer using emoticons outside punctuation. They convey additional information (tone especially) separate from the text's direct semantics, so I usually treat them as an additional part of a sentence (though not so much a linguistic part) coming after a final punctuation mark. They're not words in themselves, so placing them within punctuation seems even less "correct" to me.
When it comes to instant messaging, I tend to get lazy and drop (some) full stops that occur at the end of a message.
Hooch wrote:From what I know, ">_>" or "<_<" indicates the breaking of eye contact -- shifting eyes.
In my circle of friends and my main online communities (...emoticon conventions seems to differ by group), it tends to mean that and also a sideways glare at a person. Expressing disapproval or disbelief. I, personally, tend to use the mouthless >> or << to indicate some form of shame - well, not quite, but to "break eye contact", pointing at myself for something.
And that was a horrible explanation.
Bobber wrote:A relevant problem is smilies in parentheses. "I'm feeling good today (because I ate candy :-)) but I have a dentist appointment tomorrow." looks really awkward. The solutions I can think of are putting a space between (as in "...today (because I ate candy :-) ) but...") or letting the smiley's mouth carry both the emoticon meaning and the parenthesis meaning (as in "...today (because I ate candy :-) but..."). I don't really like either of them though.
Personally, I add spaces within ( at both parentheses just to make it even ;D ), and even if the emoticon doesn't use a parenthesis.
> I'm feeling good today ( because I ate candy :-) ) but I have a dentist appointment tomorrow.
Your last option can be ambiguous, though - certainly my first reaction is not to close the parenthetical statement while reading that. And what if you have several sentences within that parenthetical statement? D; (Yes, I know, it's horrible style... but in informal writing - like on forums and when doing some serious ranting/explaining on instant messengers, I tend to use parenthetical statements to convey relevant but not directly useful information - like background explanations to whatever fact that I'm presenting - both inline in a text and at paragraph's end, like I'm doing now.)