It's a great idea, one that I've toyed with quite often. I had planned to post a topic listing the "big ticket" items I've got on the list (the to-do list has a million smaller items) and let people vote. But, to be completely honest, I don't necessarily want to be bound by the results. Sorry!
Of course I want to implement the features most wanted by the users and that will provide the most benefit, but not all features are created equal. Some are much easier and less involved, some are dependent on other items, some just don't make much sense
now but will later. And, of course, I don't want to provide ammunition for my competitors.
But I'm definitely still considering it.