I (mostly) download the thumbnail and give it the same name as the file, often adding the artist's name to both. Some thumbs aren't informative, but usually I can just browse through the thumbs in a folder on a backup CD without having to unzip everything. (Ya, Carolly, wish I had started earlier.) No commercial use includes all renders, movies, etc. Some artists like Catharina have given textures free or cheap for personal/hobby use, and then had a higher license cost for commercial use.