Sometime back, there was talk of Google Base, a databas-ish product coming from Google. Let me let a summary from their blog explain it…
Rather than impose specific schemas and structures on the world, Google Base suggests attributes and item types based on popularity, which you can use to define and attach your own labels and attributes to each data item. Then searchers can find information more quickly and effectively by using these labels and attributes to refine their queries on the experimental version of Google Base search.