The goal of this collection is to be a definitive collection of all isometric tiles on OGA, regardless of style or license. I hope to eventually go through the entire archive to catch any older ones that might have been missed. If anyone would like to be added as a collaborator, or sees something I missed or that they would like added, just leave a comment.
For isometric characters, see: http://opengameart.org/content/isometric-characters
NOTE: I have decided against including any of these: http://opengameart.org/content/fantasy-rpg-vector-art for two reasons:
1) they are broken up into a bunch of individual entries which would take up a huge amount of space, and are already handily collected at the link above, and
2) many of them aren't really isometric.