Put a link to it at your web-site, blog, forum, Facebook page or make your Twitter followers aware of your experience; add the link to social bookmarking sites, etc. - warn people you know all over the web, so that they won't repeat your mistakes.
By doing that, you will push your complaint higher and higher in Search engines and more and more people all over the world will know what they are getting into by trusting sneaky companies or by buying sub-quality products.
Please, log in to get access to your personal widget, containing items that you blacklist, otherwise the items will be from the frequent complaints list.
Let them know -- who is forewarned is forearmed!
Spread the word about your Blacklist. Insert the widget code into your blog or website and let your readers see the company, product, service, and other items that pissed you off. The widget will be automatically updated each time you add or remove a complaint from your list.