This is the answer lizardqg, one of the moderators gave a little while ago. "The Hall of Fame is a celebration of dedicated community members who contribute great content. Every month, we’ll select 100 community users who ask great, thought provoking questions, provide others will helpful answers, get to know people via the comments section underneath answers, contribute often, and are just simply good community members. Give it your best shot and you could be featured here month after month!" I can't come up with a better explanation, so I hope the cut and paste will be forgiven.
I think the contrast between the number of questions you asked and the number of questions you answered has to be very large(to the positivity of the number of questions answered). You also have to have answered a lot of questions.