Another option could be to publicly show the votes from each of the member groups. This way no one can tell who voted for whom and it would help stop people gaming the system using socks. For example, the following distribution would look a little suspicious:
member123 [+5]
Brand New: [+10, -0]
Newbie: [+0, -0]
Jr. Member: [+0, -0]
Member: [+0, -0]
Full Member: [+0, -0]
Sr. Member: [+0, -0]
Hero Member: [+0, -5]
I will do this. Not sure how yet but it's definitely something worth implementing.
It's not critical for now as I manually send passwords to people asking for them.
I like this idea the best, opening it will just mean more drama and fake votes from retaliation (disclosure, haven't used it yet).