No one that I know of has done more over the years to help define what a Web site should say than Jakob Nielsen of www.useit.com.
He is direct, knowledgeable, and almost always right. His message for Web site language and content has been consistent, and extraordinarily useful for manufacturers.
The latest post on the subject comes from his Alertbox newsletter. Writing Style for Print vs. Web follows Jakob's mantra that prospects are in a different condition when they visit your Web site, compared to when they encounter a brochure or other printed media.
I've always described the distinction like this:
Printed media introduces prospects to things they didn't know they needed. The Web introduces prospects to things they already know they need, but aren't sure where to find them.
For anyone interested in maximizing their manufacturing Web site, you'd do well to read through Jakob's legacy work at UseIt.com. Here are some other related pieces on his site that can help you improve your site's effectiveness at gaining new work and prospects:
Ha! I like the comments from Information Pollution: "Spam is... Attention Theft!" I love it, and couldn't agree more. Good stuff.