Cubescape is a great AJAX based web site that lets you drop cubes in a field. This lets you come up with elaborate isometric art, depending on how much time you are willing to spend on it. Till recently, users could save their creations, and people could browse through them. That functionality has been recently disabled, although there are a few great creations still searchable through Google images.
Depth can be very misleading in Isometric art, as everything actually looks the same distance from the viewer, what you see above is not a solid block for example. Look carefully at the shadows, and you will see a hole in the block. Once you have created a cubescape, you can play it back.