A really cool, functional portal gun from the guys @ Hackaday.com:

I was out to lunch with a couple friends, brainstorming ideas for fun projects when one of them says “Wouldn’t it be cool if we could build a working gravity gun?”. We: all immediately concurred that while it would in fact be cool, it is also a silly proposition. However, only a few seconds later, I realized we could do a display piece that emulated this concept very easily.

[Hackaday]