A while ago, Derek Sivers had a blog post about how with most of his ideas, the first thing he does is sketch out the database schema. That seems to help him think it through in the same way. His blog has been redesigned since then, but here is a link to the details he used to have online, including database schema and Rails RESTful routes:

http://web.archive.org/web/20100926194455/http://thoughts.pr...