Hacker News' policy is that some self-promotion is allowed, but it can't be the focus of most of your posts. There are people who occasionally post their own articles and such but if the majority of their posts are interesting other things, nobody complains (much).
On the other hand, I've flagged items lately that were posted three times in a day by a new user who apparently hadn't read the submission guidelines. That just looks like spam, even if they're "on-topic" for the HN crowd.