A former co-worker passed along this cool pointer to me. It won Best in Show at Under the Radar this year.
The video shows how, using Dabble, a single spreadsheet of data can be massaged into a collection of related tables. One of the cooler things was watching the extraction of repeated data into a related table. I kept thinking, this would be a very slick way to create models in Rails. I could almost see the associations being written as the relationships were being created.
The Dabble site doesn't say anything about creating a custom UI or application logic on top of the data, but it seems like a natural progression to me. Since it will provide an API for doing mashups, that may not be too hard to do.