I suggest allowing feedback to count for votes — but _only_ for purposes of the "hotness" calculation.  There'd be no change to anyone's rep, but marking that you thought a question was helpful could bump it up on the hottest questions views.

The downside is that we'd need to guard against using this mechanism for spam by asking a question and then sending a bunch of anonymous feedback... but I don't think that would be a problem as a spam question on this view would be quickly spotted, closed, and deleted.