It can't, really. There's nothing remotely like web indexing in a crypto currency. Indexing websites is massively storage and bandwidth intensive, something which a distributed blockchain is not designed for. It's a nice idea to make a distributes search engine, but has nothing to do with Bitcoin.
Yeah, I wasn't implying that the specifics of BitCoin would work well for a hypothetical SearchCoin. NameCoin is feasible because the volume of data is much smaller, both for keys and values, and updated infrequently.
