Don't know if this has been discussed here yet but, I must say, this one looks pretty authentic. It appears as if someone managed to fit a high-intensity blue laser into what looks like a Playmates Diamond Select TOS phaser and killed a balloon with it - rather quickly, too. While it's probably easy to fake something with this with the right kind of post production tools, it would be interesting to know if this is the real deal or not. Anyways, here it is. Quite impressive, if true.
http://now.msn.com/now/0426-real-life-phaser.aspx#scptmd
Edit: another article on the subject: http://www.geek.com/articles/geek-cetera/homemade-star-trek-phaser-really-will-stun-you-20120426/
http://now.msn.com/now/0426-real-life-phaser.aspx#scptmd
Edit: another article on the subject: http://www.geek.com/articles/geek-cetera/homemade-star-trek-phaser-really-will-stun-you-20120426/