While on a Friday evening outing with few colleagues, I got to know the history behind saying "Cheers" before you taste your drink.
One theory says the clinking of glasses was to ward off the evil spirits. The more popular belief is that when you crash glasses together, it causes the drinks to spill over in the other glasses, hence establishing the faith among the drinkers that none of the drinks is poisoned.
Interesting stuff, isn't it?