This is a very basic product, don't get me wrong, basic is a good thing.

Some feedback: Registration is very nice, simple steps. However, log in with Gmail/Facebook/Twitter might be a nice option in the future too.

How do you handle links? I didn't check this since I'm on mobile but nofollow would be a good idea to prevent spammers. Maybe even add Google's recaptcha to prevent spam bots for anonymous users/on registration?

For groups/companies, it might be nice if we can register a sub domain and allow others to post new discussions in there to keep it all grouped. But that would mean there'd have to be a moderation option (?).