AnkerCAD is a freeware program for building virtual models with bricks ('AnkerSteine'). It is a spin-off from BlockCAD, and was inspired by Burkhard Schulz, who has made all the stone definitions.
If you don't know what AnkerSteine (AnchorStones) are, you can take a look at the manufacturer's page, or one of the enthusiasts page.
With AnkerCAD you can save your models, or save pictures of them (.bmp, .jpg), even reuse a complete model as a part in another model.
Everything can be controlled with the mouse, but it's also possible to use the keyboard for most of the commands, making 'routine building' more effective, and there is a minimum of text involved, to make it easier for kids,
AnkerCAD is freeware, but if you really like the program, I would be happy if you send me a piece of (real) Lego - yes, I'd prefer Lego, but of course you may send me an Anker-stone instead, if you really want to, and maybe a postcard from your home town. My mail adress can be found in the About... box in the program.
AnkerCAD was started as a copy of BlockCAD 2.5, in the summer of 2001, when Burkhard Schulz sent me some stone definitions, and asked me if it was possible to do some small modifications. Burkhard has made a tremendous job, producing all of the stones in a very short time. I have only patched the BlockCAD program a little.