This morning Alexa opened its Alexa Web Crawl to the public, offering all comers the chance to create their own customized search engines. “Anyone can also use Alexa’s servers and processing power to mine its index to discover things – perhaps, to outsource the crawl needed to create a vertical search engine, for example,” John Battelle, who broke the story, explains. “Or maybe to build new kinds of search engines entirely, or … well, whatever creative folks can dream up …