Introduction to writing spiders and agents
Advice and warnings
   1. Observe other people's intellectual property rights
   2. Adhere to web site's usage policies
        They can block your IP address forever
        Don't spider eBay or Yahoo!
   3. DNS Registries only allow a limited number of requests from a single IP address in a given day
        (or so I'm told)
   4. Be responsible...
        Don't write spiders that collect email addresses for spam mailers
        Don't write DOS (Denial of Service) agents