Have a stand or NPC in each town that when clicked on, gives you two options, one is open a form on the screen in which you fill out with the topic/suggestion, and a second for viewing other peoples suggestions.... similiar to the AH but with the abiliity to access in any town, or major towns. 

People who want to voice their opinions will have easy, in-game access, while other players who care will be able to talk about it live in the same area of which they are petitioning!