Great plugin! Well done. And to do it for free is great.
I was looking at the Post Expirator plugin (http://wordpress.org/extend/plugins/post-expirator/) and was wondering whether you were considering adding similar functionality to Idea Stream?
What I'd really like as administrator is to set a fixed time period (say one month) on all new ideas - but also have the flexibility to change it for some of them.
What do you think?