Jeremy’s comment policy, #4 (don’t provide a URI to a non-weblog site) site is something that has always bugged me but I’ve never pinned down. I’ve had a fellow weblogger comment with his URI as his business site instead of his weblog before, presumably to help generate inbound links. Generally in these cases I nuke the URI but leave the comment.
I’ll usually use my MetaGrrrl URL and email, because I’m usually posting as personal-life-me-Dinah, but it’s conceivable that I might wish to make a comment as my professional self, in which case I would use a work one. It’s not necessarily trolling for pagerank; it’s another aspect of conveying mood. Online we’re missing tone of voice and clothing; we use the tools we have.
I also, by and large, remove links to company websites, though I have never made it ‘official policy’.