I have some ideas, but I don't want to make them unless they're actually needed. Just confirming it has to be done before I do it. :p Please let me know if you have any specific ideas about what each one should look like, and what size they should be.
We do need these icons. The resources table are implemented since 0.31.0.
The size of these icons should match that of the existing ID type icons (e.g. activators, global variables, factions, ...). There plenty of these in the repository.
Please pay special attention to sound files. We already have icons for sound and sound gen. The sound file icon needs to be distinguishable. Ideally all the resources icons should share some visible properties.