All of the Invigorator versions as well as ProAnimator come with preset material libraries. In our case, Material means any combination of base color and images which can be applied as conventional image maps, reflection maps, bump maps or transparency maps. Throw in settings for specular highlights and you can see that Invigorator materials are highly flexible and much more than a collection of bit-mapped images.
So, where do you go from there?
You can modify any of the preset materials and add the modified versions to your materials library.
You can also use any of the textures you've gathered for use with Lightwave or any other app as part of Invigorator materials. You will likely need to either crop or resize some of the high-rez textures out there, or you'll be wasting processing time dealing with resolution you don't need. (You may need to convert the format of these files to tga in Photoshop as well.)
As for sizing these additional textures. the best advise is to open some of the default images and use them as reference. You can drop any of these images into the folders where the Zaxwerks maps reside, or create and organize your own folders.
Some people like to keep custom material libraries and images with their associated projects. Others like to build monster libraries and keep the additional tga image files with the default Invigorator files.
At this point, I know of no website where Invigorator material libraries can be uploaded and shared, but who knows what will happen if there's enough interest.