I got a Groupon deal for Voodoo Zipline (located inside the Rio Hotel) while I was on vacay in Vegas. The hours are awesome since they open somewhat early and late so you can decide if you want to zip line in the morning or night. The only downside when I went (at night) was that there was only one employee checking in all of the zip line customers. It took an hour to get checked in and then you have wait for a text message to be sent in order to go into the VooDoo night club two doors down to get to the zip line area outside.
The zip line ride is pretty quick (about 1-2 min) and the speed is somewhere around 30MPH so it's not scary or fast at all (in my opinion). They take GoPro video footage while you're on the ride that you can choose to pay for upfront when you're checking in and a few photos that you can buy after the zip line ride. You also get a free drink voucher to the club if you buy the Groupon deal.
Since the wait time to get checked in was much longer than the ride itself, I don't think going here is worth it unless they staff more employees or you go during a time that no one else goes. The ride itself is mediocre (since I had higher expectations of it being scarier than it was) but it was cool to say that I zip lined in Vegas.