I've just finished writing two vastly different e-mails to two different companies.
I spoke about these two companies before, and suffice to say that each handled my situation in opposing styles. One company went above and beyond when they sensed my displeasure, and the other failed horribly and lost my business.
I believe in follow up - I sent off these emails to let the people in charge know how I felt about interacting with their company. I praised the good in the one business, and ridiculed the horrible service from the other.
The only way companies know how we like (or dislike) them is by feedback.
Most people punish poor service by giving feedback with their wallet - they just won't go there again. I like to take it a step further. The President or Head Honcho of a company won't know if I stop going there by looking at the sales sheets, but he'll know when my email crosses his desk. I also like to let the guys in charge know when one of their own has done the job right - these people deserve to be rewarded from higher up. How are they going to find out if no one tells them?
Get out your keyboards and use the Internet for what it was made for - interaction and feedback. (No, the Internet was not made for Porn - it just seems that way.) Think about the last good or bad interaction you had with a company and let them know.
It'll make you feel better.