I'm making a platformer that is going to be viewed in isometric, I am currently up to getting all my stuff off of paper and onto the computer screen, however I was wondering if there were any apps out there (preferably freeware) that would be handy for making isometric tile-art. I was planning to use a 3d map editor and 3d polygons, but I think my concept would work just as well with sprites maybe.

TileStudio has been pretty handy for me.

http://sourceforge.net/projects/tilestudio/

Well, if you're looking for placeholder art, you can always rip the tileset from Age of Kings. It's huge (1000+ tiles) and easily extractable from the game. But if you're looking for something you can redistribute, this won't help you at all (unless you like being sued for copyright infringement).

I use a 3d program to prerender isometic art. I just set up one camera angle (camera moved way out but with the zoom way in to get rid of distortion). I set the scene up once and save it, then I just swap the objects out, and I render them out in 32 bit so I already have a mask for it. This means all the tiles have the same lighting and angle, and it takes care of shadows.

The great thing about doing it this way is if you're rendering them into 2d sprites, your 3d models don't have to be very detailed, and it doesn't take long to build a model with enough detail to work as a sprite. It saved so much time on the games I've used it on. Of course, it all depends on the art style and the size of the final sprites.

Hanford