Here is my suggestion: Open a Nxt account for voting. If someone wants to vote, they can send the account a public AM (Message). Use a topic # that people can use in their voting message. For example, message says "I vote for option #2 on topic # 112" That way, it cost 1 Nxt to vote but the account doesn't actually receive any Nxt.
I like this idea also - at least we are now starting to think about a Nxt way of voting!