Increasing Viewer Engagement

So last night while I was streaming Warframe, someone started watching and they were like "HEY! DO YOU GIVE AWAY FREE PLAT?!" and that got me thinking;

1. Do people actually do that?
2. I bet that's a great way to increase viewer engagement
3. Is that why everyone who doesn't stream regularly is like "OMFG I'M GIVING AWAY __!!!! COME WATCH!"

I haven't really had a chance to brainstorm, though I have actually been streaming pretty regularly, what with the PS4 making it so easy and all that jazz... In any case, I'd like to brainstorm on ways that can increase viewer engagement/tie people into the streams! Are there any ways you've thought of/used before that get people to come and stay and interact with you? This is of course not counting giveaways, I've actually thought about that kind of thing before. I would much rather go ahead and do giveaways on my YouTube channel, rather than my stream, as almost no one watches me when I stream... Unless of course I get the rest of Okamigakure to come and hang out too. 
What other ideas can we come up with to get people to hang out in a stream??