These are called "emoticons" or "smileys" and are pictures (i.e., facial expressions) that you "draw" by typing a specific series of characters. It's an attempt to add emotion, inflection, tone, and humor to the rather bland world of email communication. There are hundreds, and many versions of any one exist. People tend to love them or hate them, although sparingly using the more common ones is fairly well accepted. Along this same line are also acronyms that serve as shorthand in email or chat rooms. I'll list a few of the more common ones and include some links if you want to explore further.

Smile, jest
Unhappy, "unsmiley"
:-I Expresses indifference
:-O Surprise
> Mad
:-D Laughing
Wink, jest

IMHO = In My Humble Opinion
AAMOF = As A Matter Of Fact
BYAM = Between You And Me
LOL = Laughing Out Loud OR Lots of Luck
TTFN = Ta Ta For Now

Another piece of information that newer users may not know is that TYPING YOUR WHOLE MESSAGE IN ALL CAPS IS CONSIDERED YELLING and generally not appropriate etiquette (or, as they say for the Internet, “netiquette”).

Here are a few links if you want to explore the world of emoticons and acronymns in more detail:
www.randomhouse.com/features/davebarry/emoticon.html
www.kidspenpals.about.com/kids/kidspenpals/cs/emoticonsandacro/
www.computeruser.com/resources/dictionary/emoticons.html

OK, so I am a computer dummy - Please help me. Exactly what do the little message icons (?, smiley face, or whatever the other signs are ) mean on the postings?? thank you .