I've been pondering over the idea of what it would mean to allow heterogeneous list items. By heterogeneous, I'm referring to different schemas for individual list items in the same list. For lists that span broad topics or incorporate different types of information, the list creator will find that they end up adding a number of different item attributes to accommodate all possible cases, yet only a fraction of attributes are actually used or even relevant to most items.

I imagine that supporting lists with heterogeneous schemas would introduce a great deal of complexity for the application at this stage of the game. As a compromise I was thinking that an option to be able to hide the unused data fields in on the item view page would present the authors' data in a more focused manner.

That said, I fully support the idea of showing all of the item's attributes with the "Add Data" links as it encourages the participatory underpinnings of the site. This led to the idea of displaying the unused attributes in a "reduced" manner. For example, they could be packed together in an "Unused|Other|Additional Attributes" section at the bottom of the Item View. This would seem to create a nice compromise between allowing content creators presentation flexibility while retaining the tangible invitation for visitors to contribute. Having all three options available would be bonus for the content creators , but I certainly understand if that strays too far from the site vision.