Another thing to keep in mind with all of Jakob Nielsen's top 10 lists: they're all just guidelines, and even Nielsen himself realizes not ever "rule" will apply to every site. In fact, he only reasonably expects a few.
This is a bit of a side comment, but there's always been a bit of Nielsen bashing, and his latest list has generated the same type of crap: "#10 is stupid, it doesn't even apply to me", "I violate #4 on purpose because...", etc.
I was lucky enough to see Jakob Nielsen speak in person in San Francisco a couple years ago. One of the first things he said in his keynote, is that he has *never* expected every site to obey every guideline he comes up with. What he's done is notice a great many sites violating some fundamental guidelines, and he puts out his lists so that others can avoid the same mistakes. For some sites, many of the guidelines simply won't apply.
For example, in his Ten Steps for Cleaning Up Information Pollution, he has '#2. Don't use "reply to all" when responding to email. Abide by the good old "need to know" principle that's so beloved by the military and send follow-up messages only to those people who will actually benefit from the reply.'
I've read posts on some sites saying this is stupid, because sometimes reply to all facilitates a group discussion. I say, that's missing the point entirely. The second part of that "rule" is to abide by the "need to know" principal. If the email is part of a group discussion, then "reply to all" is perfectly valid. What the rule is intended for is when people (and I work with plenty of them) reply to all for *every* message they receive, even when the reply is directed only at the sender.
Ok, enough of a tangent...