Plugin to gather approvals / signatures on an initiative?

Yea like Jay pointed out, there are inbuilt features that can help you achieve what you are asking.

You may also want to peruse the plugin and theme-component topics to see if there might be some things that can enhance your forum features. I was thinking the Custom Wizard plugin might be of use to you. We also have a policy plugin, calendar and events plugin and topic voting plugin that might interest your organization. Also, topic templates are very useful.