Totally agree, but if you are going to capture little bits of info say: Zip, Sex..etc From experience I was wondering which was most useful to increasing activity and membership and how people creatively leveraged them.
Well, personally I don't think that any of the other fields are worth capturing until you have started building a relationship with the user... then, it depends on what sort of information you want to send them. What job they have can be very useful (for example, if you're operating within the construction niche and your message to project managers is very different from your message to architects), but those are all things you grab in the form after the one that grabs email...
I think which elements are essential really depends on your site and what you're trying to communicate.
