This may seem like a really obtuse topic to discuss. Which is precisely why so many professionals run into trouble by not putting some thought into their font choices.
First, here's where the wrong font can give users and companies fits:
1. On the company web site: fonts look differently when viewed on different browsers; and smaller. For example, Arial is so popular on Windows that it's the preset font on Microsoft products. Macs don't have Arial. The equivalent is Helvetica.
2. On e-mail: same issue. The other big mistake that users make is taking a little too much latitude with their creativity. It's one thing to use the font Comic Sans Serif on your own time putting together that PTA flier. Don't use it on an e-mail going out to clients. Times Roman (or Times on the Mac) is the font equivalent of the traditional corporate grey pinstriped suit.
3. Consider a company mandated font. Why spend all that money on coordinated marketing collateral and then have your employees sending out e-mails, blog postings, Powerpoint presentations and print materials in a tower of Babel of various fonts? Keep your look consistent across the board with one or two universal fonts (and clear directions under what circumstances each is used).
Tomorrow: Which of the "safe" fonts is the most universal and therefore "safest" to use across the board?