Just a suggestion, but with all of the members we have, I think there must be a few people that can develop quizzes. If you develop a quiz, show sources for your information and it is accurate, this can be a quick way to add more quizzes. People who have their Quiz published get a Spark People T-Shirt and recognition for their efforts.
SP can take Quiz submissions for the next year and have a deadline for when they are due.
I suspect it might generate a lot of good things for SP and the members that develop the quizzes would feel great and those that like quizzes could be challenged even more.