The Orchot Tzaddikim has a little different approach in explaining the power of the tongue. There is an attempt to specifically show how speech can be used for good, or for harm.
He first gives examples of very grievous sins that are related to speech. Perhaps by enumerating some of them, an impression will be made on the reader, to take this matter to heart.
Negative speech can lead to be a מלשין, one who snitches on another Jew to the authorities. It also leads to רכילות, idle gossiping. Improper speech can also consist of levity, flattery, and outright lying. A false oath comes from speech as well.
After listing and realizing just how detrimental the power of speech can be, one must realize how speech can be used in a positive way.
One should consistently speak words of Torah and the importance of fear of Heaven. He should use speech to give rebuke, when necessary. He should command his children to observe the Mitzvot. Positive speech can console the mourners, and comfort the poor, with soothing words of goodly consolation. And finally, one should only speak truth and utter song and praise of Hashem.
There is no question that reminders of the power of speech, should be made on a regular basis. Without such reminders, it is easy to forget just how careful we must be, every time we open our mouths.