People downvoted and flagged this, but I think a comment like this is ok when the author is a regular user, doesn't do it often, and is up-front about it.
I don't think so, if the links are relevant enough and it isn't overdone.
If someone's using HN primarily for this purpose, that's a different story. But seibelj's most recent comments include housing, transportation infrastructure, freenet, and software licensing. Sounds like a real community member to me. :)
iOS: https://itunes.apple.com/us/app/lendingclub-order/id10461141...
Android: https://play.google.com/store/apps/details?id=com.jamesys.le...