That is the title of a terrific book on web usability by Steve Krug. He argues a pretty common sense approach to web usability that I find pretty compelling.
Take his First Law of Web Usability: Don't Make Me Think! His contention is that web users are scanners not readers (not unlike ad readers, IMHO), and each page, and the elements in it, have to be as self-evident as possible. Web visitors should be able to grasp instantly (and thoughtlessly) what the page is for and why they should care to stop there. It starts with design (bad design will usually obscure great language), but the language is the "closer." The design steers the visitor to the words, and the words have to be simple, self-evident and compelling enough to entice the visitor to take the action you want.
His Third Law is, from a copy point of view, a close corollary of the First: Get rid of half the words on each page. Then get rid of half of what's left. Think "Scanners, not readers." Think "Short and Sweet." Many of the least user-friendly web sites out there are those where the company thinks of their site as an online brochure or, worst-case, an online direct mail piece. Here's where, if I might be permitted a short plug, professional copywriters are worth their weight in gold. A good copywriter should be able to cut the first 50% of the words in their sleep while maintaining, and often enhancing, the message.
Both of which reflect Kelberer's First Law of Good Business Writing: Given a choice between clever and clear, choose clear every time. Fewer awards, but you'll laugh all the way to the bank.