A life-size Imperial AT-AT. If Lucas gives the go-ahead, I'd love to see it. Heck, I'd pay to see it. As far as effectiveness, I think every 30+ year old geek-at-heart would have it defeated in about 30 seconds. We've seen the rebel manual.
Or as That Guy put it: "So, instead of Luke Skywalker in an A-Wing and a tow cable it will be Cleatus in an '82 Chevy C-10 4x4 with a Gadsden flag bumper sticker and a Warn winch."
That's a much more colorful way to put it.