I barely use it anymore, but I used to pour massive quantities of Splenda into my coffee every morning. When I was really sick, I also used to suck on lots of sugar-free candy, drink lots of diet soda, etc. My sweet tooth seems to have gone into hibernation over the past couple years and now, the thought of desecrating my coffee with fake sugar seems like a crime against nature. Not sure how I used to consume such sickeningly sweet stuff all the time, but my taste buds have definitely changed.
Anyway, this article caught my eye because I remember swiping packets of Splenda from coffee shops and keeping a stash in my bag at all times. It's kind of a dense read for the less scientifically-inclined, but still pretty informative: Choosing a Sugar Substitute.
There's also an interesting paragraph near the end about the sugar content and satiety factor of liquid calories...although for my own sanity, I had to selectively gloss over it a little, Boost in hand.