Is there a way to see thumbnails of all the materials in a scene? As someone who comes from a Maya background, I got quite used to being able to open Maya's Hypershade window and see all the materials in my scene at a glance. However, in Blender it seems that the materials tab only shows materials that are assigned to the active object. Is there a way to display a material preview for all materials in a scene?

Currently, the only place I can find the materials added to my scene is in the outliner in datablocks mode, which shows me that there are materials in my scene, but I can't see previews of them or easily check if the textures have loaded correctly.
What you really want is an old todo item. In two ways things already possible though.


Browse the materials in memory for linking (menu button to left of button where you can change material name). It shows icon-size previews. Blender already supports popups with larger previews (used for matcaps, brushes). Something similar could be coded to be used here too.
You can inspect materials (with previews) inside any other .blend file with using the File->Append browser, it allows to go into a file and see materials. Set file browser to view thumbnails. This type of browsing could be used for linked large collections of materials, textures or images too.