Iceberg features are where on the surface they seem small and simple while backed by a huge un-seeable chunks of functionality and processes. Like their real counterpart they come in many different shapes and sizes. From the “Oh, just add an extra field to this form”, which in-fact impacts the business logic, to “Just copy this feature on site X”, without taking into consideration the processes that go on behind the scenes. I’m sure we’ve all experienced the first sort of “small change” problem before, but the second one is a lot more subtle and easy to miss.
A lot of sites successful implement a “invite your friends” feature, which grabs a user’s address book and messages each of them asking them to join. The simplistic way of copying the functionality is to think that the road to success is simply grabbing the needed details and messaging them, thinking that what makes the functionality successful starts with the form and stops with the initial message. That’s just the tip of the feature iceberg. Is it successful for another site as they have a planned out set of campaign emails they send out to an invited person, with timed followups and different possible campaign routes depending on a user’s reactions. It may well be that having a naive imitation of the feature is better than not having one at all, but it’s the compromise of deciding what to do. Is a poorly imitated, half implemented and thought out feature better than a smaller, but more complete and well thought out one.