FastStone looks extremely useful for general viewing and batch naming as you had pointed out. MindTex however doesn't serve a lot of use for me as I always produce materials from scratch now (using heightmaps). While normal map conversion is handy if you're basing it off of a diffuse, it's not near as accurate as using a heightmap. The reason being is that any light/dark areas aren't explicitly representing true height values (when extracting from a diffuse image), so it skews the ending result. For instance, a dark colored bolt or rivet will be considered to be depressed into the surface (even if the intended appearance is that it sticks out of the object) simply because it's calculated from a diffuse.
If anyone remembers crazy bump, I own a copy of that (which really just collects dust for me) and it attends to the same functions if need be. The big thing now is I've switched my workflow to Allegorithmic's Substance tools, and it fills the role of my material creation since I prefer to have control over the look of my models from start to finish. However, for anyone who doesn't mainline their approach via modeling or even Substance Designer as standalone material creation, MindTex is definitely your next best option.
Mainly because of dynamic control factors, the old fashion image copy methods of rummaging old photo repositories are becoming obsolete for the industry. The only real world data being sought after now are being translated into Mega Scans and different information maps of the like. This largely has to do with new rendering methods such as PBR and greater processing power to handle more complex and dynamic materials. Old image dumps such as CGtextures are hopping on board with getting scans on their sites now as a response to the change in workflow. For me personally I've found that id4's dynamic lighting actually achieves some very good results for an old engine. Banking on a more modern theory of less lighting info (in the diffuse) and more reliance on normal maps. For a modeler like me, it's a lot more attractive than the very subpar bumpmap/lighting pass in a similar dated engine such as Source.