Must reply, to vote on a poll. - Exists?

[Fulla]

On a certain site I visit, where you can Download several things.
Each item downloaded requires a password to extract.

To get the password you need to reply to the thread in which you can then see the password 'appear' in the original first post.

===

This made me think,
In a similiar fashion I was wondering is it possible, does a mod exist that?
Only allows you to (see OR vote) on a Poll once youve replied.

On many forum/polls random 'negative' entries can be very annoying.
So having an alternative poll possiblity where Users must first reply, for e.g. giving a reason why they/what they voted for and then being allows to vote would be very useful.

thx.