I used the Vicks Cool Mist Humidifier. Picked it up at Target for $40.00
From a previous thread:
I used the Vicks version. I bought a 2" to 3/4" PVC Adapter and siliconed it to the top of the unit, I then threaded in a peice of 3/4" brass all thread wrapped in teflon, next I threaded on a 3/4" PVC Female Fitting, Lastly I picked up a 4 1/2' long Washing Machine Flex Return Pipe and fit it over the 3/4" PVC Fitting. Ran the Flex line up the back of the Viv and in through the top ... works great and was super easy to peice together. Aside from the black silicone (All I had and didn't really care as it's hidden anyways) even looks pretty clean.