Q Block is a neat little Flash toy that lets you create 3D pixel art similar to the look that's being used in From Software's new project. It's from a completely unrelated developer, but cool nonetheless. You can browse the ones that people have already created, and start building by clicking the EDIT> button.
Press the Clear button, and you'll be presented with a blank white canvas, floating in space. Clicking and dragging around the screen will rotate the object, while the three buttons in the upper left determine what happens when you click on a block. Paint will color the block to the selected color, Attach will add another block sticking out from the side you click on, while remove will unsurprisingly remove one.
This method is a little unwieldy for filling large areas quickly, but it's perfect for rotating, making small adjustments, and tweaking the look of something. For large areas that you need to fill quickly, click the "Show Canvas" button.
This will display a 2D canvas that you can paint and erase on, as well as showing your different layers available. Draw on this canvas and it'll be shown in 3D back in the main area. You can copy layers, clear layers, and even extrude something through all the layers. When you're finished, hit save, give your creation a title and list your name, and that's that, it'll give you a permanent link to the file so you can share it with all your friends.
Play with Q Block here!
If you come up with anything awesome, be sure to share it.