Just a quick thing I made this morning since I woke up so early!
This example requires PS 2.0 to run, but only because the 3D Box object doesn't have a runtime opacity option (and the edit time opacity option doesn't work, either), so I had to opt for using the Opacity Plus shader to achieve it. Because of this, there's noticeable slow down when you have more than 25 3D Boxes, which shouldn't be the case if it could use normal opacity methods instead. Would it be possible to let the 3D Box have opacity like normal sprites do? I'm sure it would come in useful for other things, too.
Anyhoo, this is more of a pretty effect than anything useful, but I think it's a pretty cool one for how simple it is.