Mavention Insert Table of Contents is now available as an App for SharePoint.
Design Manager allows you to quickly implement your user experience in SharePoint but if you want to build a great public-facing website you should build the Master Page and Page Layouts yourself instead.
On your public-facing website use the XML Sitemap and Robots.txt file to optimize your website for Internet search engines.
When building public-facing websites with SharePoint 2013 you should disallow anonymous users from overriding the Master Page on your website.
Using Device Channels in SharePoint 2013 you can separate your authoring and publishing experience. This will allow you to optimize your public-facing website for visitors and search engines without losing any of the standard content management capabilities of SharePoint 2013.