We have added a new page to the wiki titled Shader requests. This is intended to provide a place for people to post ideas related to new shaders for use in FlightGear.
But this is also meant to be place for aspiring shader developers to find interesting ideas for new shaders. In the past, these ideas were often spread over many different places, such as forum or mailing list discussions, and often ended up getting hidden rather quickly. So if you have ideas related to improving existing shaders or creating completely new ones, please add your ideas to the Shader requests page.
And if you are aware of any ongoing shader development efforts, please also add those there. Consequently, if you want to get started creating shaders for FlightGear, please make sure to check out this page.
I have already added a handful of ideas from the forum.