My entry:

The coolest thing I have seen done with 3d printers so far is the fabrication of AR-15 lower receivers. Long live the second amendment. Also, I've seen some undescribable geometries that really blew my mind.

My dream machine would have a HUGE build platform. Currently, I'd like to build an oddly shaped part with dimensions around 19x10x3 which is slightly beyond most machines (that I could ever hope to afford). Another thing is speed. I would love to have a FAST printer so I could give manufacturing a go.

Fingers crossed!