First off, this is pretty sweet. The SEO dashboard and result preview are great.

We have our own set of SEO functionality that we include on every build but the dashboard and result preview are nice improvements.

Here's what I'd recommend adding - I'd be glad to help out and contribute since we already have this functionality.

1. Site canonical domain name- set the default canonical domain name to be used for the site.
2. Page by page canonical link override - allow the canonical url to be overridden page by page (we also auto generate this based on the url, if not set)
3. Robots meta follow options - allow the follow options to be set by page
4. Simple char limit / warnings for meta title and meta description. Knowing that we're over or under the limits in the dashboard is great, but it's easier if we have a simple data type to show a simple good or bad alert.