I think there's a difference between these situations:
1- Someone posts a thread, "hey guys, we've updated the genetics calculator to reflect the latest discovered genes. (URL)"
2- Someone posts a thread, "hey guys, we've updated the genetics tutorial with new animations and a new section about sex-linked traits. (URL)"
3- Someone posts a thread, "hey guys, I've just completed my new corn site, come check it out! (URL)"
4- Someone posts a thread, "hey guys, I've put up my own forums on my own website, come join the discussion. (URL)"
As I understand it, the first two would be fine, and the last two are the "looky looky" types Rich is talking about. IMO the first two (like Menhir said) add specific value to the conversation here and I'm guessing that Rich would not find these objectionable.
