Rand in Brighton, and that might be Rand Fishkin, i don't know, asks: „What are your views on 'PageRank sculpting'? Useful and recommended if implemented right, or unethical?“.
Well I wouldn't say that it's unethical because it's stuff on your website. Your allowed to control how the PageRank flows around within your site. I would say that it's not the first thing that I would work on.
I would work on getting more links, having higher quality content, those are always the sorts of things that you want to do first. But then, if you have a certain amount of budget of PageRank, you certainly can sculpt you PageRank.
I wouldn't necessarily do it with the nofollow tag, although you can put a nofollow on a login-page or something thats customized, where a robot will never log-in, for example. But a better, more effective form of PageRank sculpting is choosing, for example, which things to link to from your homepage.
So imagine you've got two different pages, you got one product, that earns you a lot of money every time someone buys and you've got another product, where you make 10 cents. You probably want to highlight this page, you want to make sure that it gets enough PageRank that it can rank well.
So this is more likely a page that you want to link to from your homepage. So when people talk about 'PageRank sculpting' they tend to think nofollow and all that sort of stuff but in some sense, the ways that you choose to create your site, your site architecture and how you link between your pages, is a type of PageRank sculpting.
So it's certainly not unethical to have all the links come in to your site and then you decide how to link within your site and how to make the pages within your site.
I do think, that having more links because you have great content is a better way to rank well because it's a second order effect to be sculpting your PageRank. It can be useful but it wouldn't be the first thing that I would do.