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.
OpenGameArt.org can automatically generate a single credits file for all of the art in this collection. Please note that, while we tried our best, this file is in no way guaranteed to be accurate, and properly attributing the work you distribute with your project remains your responsibility. You'll want to load up this file in a text editor, check to make sure everything looks good (and that any special attribution instructions are followed), and then delete the notice at the top of the file, as the notice is designed to make you look very silly if you don't check over the file and remove it.