Related to the current 'Data is primary .... why?' thread, once you have your carefully crafted data-model what can you with it?
Thinking in terms of a simplicity stack of non-mutually-exclusive options (cost-effectiveness is a better notion, simple might not be cost-effective in the long term, one option should build on another if possible).
The combination of a data-model in XML Format (schema) and XML technologies is a powerful combination at the bottom of the stack, here are some expressions:
1) Schema Generated Forms (XML Editors)
2) Configuration for a data-driven/data-event programming paradigm.
3) Schema-aware "dynamic" language procedural programming before fully object-oriented.
4) Smarter generic data-browsers (query interfaces) via schemas as resource 'meta-representations'.
5) Smart (user-friendly) databases based on a conceptual/semantic data-models.
Steve