It would be great to be able to set up an Ideas portal for only a specific category (or possibly multiple categories). This would allow the "chrome" to be specific to the category and allow us to target segments of users with different Ideas Portals set up just for their needs.
Thank you for your idea. Since ideas portals can be product specific, one way to approach this would be to create a product for each individual portal you need. As ideas are ready to be promoted, you could then promote them to features in the product where you manage releases and features.
At this time based on feedback in this area and current priorities, we are unlikely to implement this idea. We hope you can understand.