For an example, I believe that Joly would be placed into either Slytherin (based on his probable expertise in potions) or Ravenclaw (because I cannot see him being evil or conniving)
Likewise, Javert could be Slytherin (do I need to give a reason?) or Ravenclaw, because he is intelligent. Or perhaps even Gryffindor due to his strong sense of justice.

I don't know if this idea has been posted already, but what are your thoughts?