The title of this post is a bit of a misnomer. It's more like what two things the web is. The web consists of content and indexes. They are both valuable because each cannot exist well without the other. Imagine a dictionary with its definitions distributed randomly everywhere in it with no order. That's what the web is like without links.
Sure a search engine has an index, but that's not what I'm talking about; I'm talking more broadly. A news article with links in is it is both content and an index. Links on a webpage are what make an index, so almost all webpages double as content and indexes or cross-references, however you want to think it.
But some webpages are used just for the index and not for the content. This is what makes search engines so valuable. A search engine is a searchable index.
One of the exciting things that has been growing on the web is web applications that help people create their own organized indexes -- lists of organized links. These web applications such as del.icio.us and stumble upon, mixx and my own web app newsconomy help automate the process of organizing indexes, sharing indexes, and adding items quickly and easy. But it's human intelligence making these.
One of the amusing things I've found is a lot of people don't get the point of web apps such as del.icio.us, newsconomy etc., and thats fine and amusing and annoying. Well if you are an Internet informationalist, someone who frequently uses and is on the lookout for information on the Internet from various sources, then these human-based web index creation web apps (or some form of this idea) have something to do with you. It's worth your while to find out about them.