Originally published in Forbes magazine. Gives address, phone number and description of products. In some cases, links to on-line product catalogs are provided. This is a good site to visit if you want to know what a company does, or if you want to know which companies make a certain type of product. Note that this is a list of manufacturers.
Some companies have more extensive data, such as product catalogues.
Commerce Inc Search Search by company, industry type, or even city. Sometimes they'll have the URL too. Anyway, this has more information than a standard phone book, so it might be worth a search. They also give a map from Mapquest. CorpTech Database of 45,000 manufacturers and developers of high tech products.