I've always wondered why Tor uses a server-based model of content storage rather than a Freenet-style, distributed, encrypted, plausible-denial model. It seems that it would be much more robust and secure, almost like an anonymous BitTorrent, if that's possible. Is this a future goal? Is it possible?
I see much potential for using encrypted, redundantly-distributed and plausibly-deniable (and better yet, hidden) storage backends for hidden services. Freenet is one possibility. Tahoe-LAFS is another. Cleversafe would have been another (perhaps the best) had it stayed open-source.
I imagine a system where each storage node is a hidden service. Nodes would link via VPN tunnels through Tor. Nodes would either have local storage, or securely access various cloud storage services. Given that nodes would only be storing splits of encrypted data, cloud storage is safe enough.
Servers accessible to users would be diskless reverse proxies, connected via private VPN through Tor, for servers running hidden services. Those servers would also be diskless, pulling both hidden service credentials and content from backend storage grids, connected via private VPN through Tor.
Very belated edit: So now we have IPFS, and it works well via OnionCat, which is an IPv6 overlay on Tor onion services. Using an anonymously leased VPS as a proxy, one can also join the clearnet swarm. Please see https://ipfs.io/ipfs/QmYKQvBsbYrRhdaGvQXcEoSam7s5gKVYULfRgNPzN5JM8N/IPFS-via-OnionCat.html. That's also available through an onion IPFS gateway at http://yvjsuxfapdwwxjrr.onion:8080/ipfs/QmYKQvBsbYrRhdaGvQXcEoSam7s5gKVYULfRgNPzN5JM8N/IPFS-via-OnionCat.html. I also have a simple onion site at http://tegggpdehz3nxzf3.onion/ that displays contents of folders added in OnionCat-linked peers. See https://www.reddit.com/r/ipfs/comments/5blmf0/ipfs_via_onioncat_and_anonymous_proxy/d9u397a/. Using IPFS through an OnionCat-linked clearnet proxy is currently a very bad idea, because throughput for IPFS nodes is ~10 GB per day. IPFS devs are working on options to regulate resource usage. But OnionCat-only nodes have very little throughput.
Tor isn't a content-storage system.
Tor is an anonymous communications system. As such, it facilitates communication, not storage.
Even hidden services are about communication. They allow you to talk to services such as a hidden SSH server, hidden mail server, or a hidden HTTP server. Anything that does TCP, really.
Tor could, however, be used to build an anonymous, distributed, resilient, working storage system on top. Maybe somebody will.
You could run a Tahoe-LAFS grid inside Tor to have a distributed, plausible-denial filesystem. To serve this filesystem(s) over out-of-the-box webservers you might be interested in https://tahoe-lafs.org/trac/tahoe-lafs/ticket/2144 .