Promotional portraits often involve creating images for different purposes. For web, a variety of media, and for unknown future promotional use. I always aim to capture the essence of people in their portraits, no matter what the purpose, but I make sure to come up with a variety of "looks".
Most recently, I photographed the Clickgreener.com entrepreneurs. They have created an online portal that online shoppers go through when making purchases. Just by going through their site, money is donated to charity (at no cost to the consumer). They wanted casual pictures of the three of them, which only made sense to do in a "green" environment.