Let viewers generate and suggest a poll.
In large streams, viewers often have great ideas for a poll on the topic of conversation, but the streamer would have to stop progress to think up and construct the poll. Viewers would feel a lot more engaged if they could generate the poll and then offer it to the streamer to run under their authorization. This happens a lot in asmongold's stream for instance. He might say something controversial, and the viewers will would love the opportunity to summarize their opinion a little more objectively than just spamming chat with two answers.