Wikihow has an entry called 'How to Grow Houseplants in Water'.
"Did you know that you don't have to grow your houseplants in dirt? Essentially the dirt is just the medium holding the plant up and allowing the roots to pull nutrients through moisture. You can throw out the dirt, and insects and disease along with it! Many houseplants grow very nicely in a simple double pot with a simple water solution, sometimes called passive hydroponics. In hydroculture, special pebbles rather than dirt hold up the plant's stem and roots."
It outlines the different items you will need, the steps, trick and things to look out for when using hydroponics to grow houseplants. 
