I just wanted to give my two cents on them, since I've seen heated debate on whether or not waterfalls should be in a tank or not, and I'm sure some people would like to hear someone's experience.

I got an Exo-Terra large waterfall for my 40 gal. tank, and wow, it's kept the humidity level exactly between 50-60%. No more misting 3 times a day! And I was worried about people who said that BP's can get in waterfalls and hurt/kill/etc. themselves, but there isn't anything in this one besides an encased pump that would be impossible for any snake to get hurt by, let alone get to because they would have to go for a dive to even get to it, which I've NEVER seen my girl (or other's) do. It's a light trickle too, so she's not afraid to go drink out of the basin. In fact, she spent the better half of the day that I put it in climbing all over it and investigating. (I had to eventually stuff paper towels in the space behind it because Loki apparently thought that it was her new hide LOL).

Waterfalls aren't for everyone, and I'm sure not all waterfalls are safe to put in a tank, but for someone with a little extra cash and trouble keeping the humidity up, I'd suggest taking a look at that brand and seeing if they'd work for you. (plus, it makes a nice, calming white noise when I go to sleep at night. xD )