I started my directory as a reference to professionals. My web site is almost a one-stop resource for all professionals, but the way directories are appearing in hudreds I don't think there is a future for general dirs.
I've started it in the idea of gathering together all the sites that were reliable for link exchange. but then I started earning some good cash and changed my mind. worked on it 7 months (in part-time) and now brings me $500/month
Boredom and money! Takes $3 to make and sell for at least $20 most of the time ( But I sold one for $60 earlier this month ) Now I'm going to try a long term directory and see if I can get my pagerank high then sell featured and regular for some money too
To develop themes and channel PR so I can dump it on any of my projects on a whim. I am actually surprised this isn't the most common answer here, followed closely by "I wanted an excuse to learn to program". Actually after hanging around DP for some time I realize that too many directory owners can't even read html / php / sql, much less write it. You guys actually count the money from your directories as income? I figured it was mostly reinvested or spent to open more directories/sites, after all they are really more resources anyway. If the money is that good for everyone I can't wait for phase II of my marketing plan.