One of my clients was linking out to real and trusted sites from pages on his site and added rel=nofollow to the links because he thought this was helping his site. This is unnecessary.
There’s no reason to put nofollow on editorially approved links.
If you write a blog post and nofollow the links on it your blog for no other reason that to conserve pagerank or think linking out to irrelevant sites will hurt your site, in my experience, you’re misinformed at best.
Google doesn’t penalise you for linking to irrelevant sites if both pages in question are relevant to each other.
Use nofollow only if you don’t want to vouch for the page you’re linking to. I often surmise Google might be taking in the quality or accuracy of your outbound links in some minor way to measure the strength of your trust, so don’t miss out because you are effectively not linking to anybody.
Also consider, the link you make might be the link that heps another REAL site get traffic from Google and satisfy Google’s users – that’s not a bad thing for anybody.
I don’t even use nofollow on blog comments (using the
free hobo wordpress plugin for comments) because I editorially and manualy approve all blog comments, and only approve the link after a number of comments from trusted users and if the site in question is a real site of any value.
I have little reason for nofollow these days. I don’t use it to sculpt pagerank, and I don’t use it in any arena where editorial moderation is in play.
I only use it for sites that don’t deserve the link to be search engine friendly and in 99% of the cases if I don’t have any reason to trust a site, I won’t make the link a link at all.
Pet hate – web sites where every outbound link is nofollowed. They aren’t suckers, they’re amadans.