It's easy to contribute 20 nonsense posts if you have to.
And if a writer wants to join, and talk about the book he is writing for example, ask questions about the cover or chapter 42, that's fine by me.
Once in a lifetime offers! and anything else with exclamation marks is not fine by me, even by regular members. That's advertising.
Announcing your book is absolutely fine though.
(And by the way, what happened to yours?
)