You can use links, webrings, and word of mouth. You can crawl (for non-web this may require quite specialized tooling), scrape, and compile a database for search (which can be done locally using whatever tools you prefer or even a full-blown webserver like gigablast or YaCy); and, to some degree, these practices themselves can be further decentralized and shared. Scaling is hard, especially if users expect immediate results or there are adversarial nodes to contend with.<p>Ideally, we could programmatically share feeds of curated and tagged information with each other that can be nested, mixed, or further shaped. Leveraging our trust in others (and their trust in others by proxy), which can be similar to some problems in distributed governance, is a p2p holy grail, imho.