I know the forticookbook is primarily a "fortigate" specific cookbook, but I think FTNT would do best if they would offer various menus for the other FortiXXXXX products. Since my earlier involvement with fortinet, you have grown your end-products easily by a factor 10x or more.
I think offering recipes for FortiMAIL would be the next best thing imho.
I deal with a little over half dozen business with fortimail , & who bug me for everything under the sun. I've made my own personal PowerPoint recipes sheets for setting up basic Fortimail from gateway to server, creating auto config backup, mail alias and groups, etc.....
For a current suggestion, if you take the most common everyday cases posted to TAC or even this forum, these would be greate cookbook recipes to start adding to the site.
It would be nice to see FTNT expand the cookbook lineup, but over all is a smart approach. It's the approach that others have taken such as Google to Rackspace.