Product Support at Get Satisfaction
If you're frustrated or pleased with a company or product, you can join the discussions at Get Satisfaction. The site is similar to the Microsoft newsgroups, with a wide range of questions and comments. Company employees are encouraged to participate, and customers help one another.
You can ask questions, describe problems, voice an opinion, or help someone else. Microsoft is participating, and there are a few Excel questions listed.
There are hundreds of other companies too, so if you're looking for help, or want to evaluate a company or product, this might be a good place to start.