If you use virtual table-tops, like Roll20, you've probably used map tiles. Sometimes you can find whole maps that work for your needs, but when you want to build a map yourself, having tiles will help you quickly assemble a custom map. For structures like dungeons, tiles can save a ton of time over building the whole structure.
I've built a script that automates a lot of the work of building a tile set. In short, you give it two texture images (one for the walls, one for the floor), and it generates a set of tiles using those images. The tiles are generated from a set of template images. You can use whatever template images you want, but this includes a script that will generate a few hundred useful ones for you.
The script lets you (optionally) apply a grid just to the floor and not over the walls - this makes for less visual clutter and makes it easier to tell the floor from the wall. In Roll20 you can drop the opacity of the map's grid so you'll just see the tiles' grid.
The included templates are for 6x6 unit tiles. Since not all textures are tileable when rotated/flipped, it can optionally generate those versions. Templates and tiles can be generated at any size.
There are still a few more features I want to implement before releasing it, but here's a sample set of about 960 tiles created at 70 pixels per square.
Tileset sample: tilemaker_test_set.zip (55.7MB)
Enjoy! Let me know if you have any comments on the shapes.