I’ve just removed nofollow from comment links for the blog. This means that anyone posting a useful and approved comment will be rewarded by an incoming link towards their site. The value of nofollow has been debated (here and here in german).
I think that comment moderation and akismet are the best way to manage spammers posting inane comments to your blog and hoping for a backlink from it. If somone posts something useful on a blog comment and is active in the web community they should be rewarded!
edit: I should mention the dofollow plugin I used to automatically remove the nofollows.
