The emails I get from my friends have all kinds of odd puncutation marks in them; a colon followed by a close-parenthesis, or a greater-than sign, followed by a colon, followed by an open-parenthesis. These obviously mean something to the people who sent them, but they don't mean anything to me. Can you help?

Your friends are using something we call "emoticons", or "emotional icons". They are symbols which represent a particular facial expression. The best way to interpret them is to imagine them as faces tipped sideways. So if you look at this one - :), and imagine it rotated 90 degrees, you've got a smiling face, with the colon as the eyes, and the parenthesis as the smile. Here's a quick "crash course" on internet emotion indicators:

:) = smile
:D = laughing smile
:( = frown
>:( = angry (the greater-than symbol is downturned eyebrows
::) = rolling of the eyes*
:P = tongue sticking out
:-/ = sad/uncertain/mixed emotions
B) or 8) = someone wearing sunglasses "cool"
:O = surprise
;) = wink
:-[ = sad

* The eye-rolling emoticon used to be very popular, but I hardly ever see it any more.