I've started working on a new overworld map for my hack, and was all prepared to do it by hand (draw it out, then look up the hex values in a table and enter them using a hex editor). I had done a search a while back for OS X tile editors, and only found a not-very-useful one (now unsupported:
Reptile). However, after I realized a few months ago that Java applications would work (from using TileMolester) I did a search for tile/map editors in Java, and found
Tiled. It's pretty simple, but seems to have all the features that I need. Plus, it saves its files as text files, and if you specify to save them not compressed, it should be easy to do a search and replace to get the hex values in. (Obviously this won't work for the continuous values [i.e. values above 80], but those shouldn't take too long to count by hand.)
I had also found a tileset for the overworld a while back (I don't remember from where), and reorganized it to the hex values. (The snowy mountains don't quite work because they're four tiles per hex value, but the rest work.) It should make the find-and-replace part of the process easier. I've attached the tileset, and put up a test map below that I created in about 20 minutes. Everything seems to work well and to be easy to use, so I'm excited to get started on this part of my project.
Two questions for everyone: does anyone else have any other FF4 tilesets? I didn't find any when I did my search a few months ago. If you do, please post them. Also, what do you use for tile/map editing? I'd especially be interested in multi-platform applications, since I might be able to use them. I thought I'd ask everyone before starting, just to be sure I had the best option available.