You may have noticed that we seem to have a bit of a thing for LEGOs here at TUAW. We previously told you about the open source LEGO design program Bricksmith, but now LEGO themselves have released version 1.6 of the LEGO Digital Designer. This cool little app lets you generate HTML building instructions for your design, check the cost of your raw materials, and perhaps best of all, upload your creation to an online gallery.
LEGO Digital Designer is a free download from LEGO.
[Edit: it "runs on Intel Macs" but is not a UB]