AppExchange but none of them are flexible enough to fit our needs. So we held a contest to build one!
Kenji776 produced the winning submission and he (again) takes home the $1200 prize for our Opportunity Questionnaire challenge. We like his solution so much we are contemplating tweaking the code and using it as part of our new scoring system on Force.com. It even comes with a nifty jQuery slider, Visualforce interface and reporting.
Great job by kenji776 as he rapidly ascends the leaderboard!