I know that several groups of people are working on this.
* FrostWire BitTorrent developers.
* zooko of Tahoe-LAFS
* A friend of mine from IRC
by xine dev
The basic idea is to embed searchable hashes in the blockchain that can't be censored. Then use these to fetch that actual data from a DHT network. This takes *a lot* of pressure off the blockchain from people who want to throw lots of data at it, and allows you to potentially use this scheme to allow gigabytes of data to be retrieved. It's basically proof of sacrifice.
I think this has many many very useful future applications. If we have our privacy aware wallets, identity, p2p communication (BitMessage or even XMPP) and distributed reputation, then together with the tools for managing multisig (distributed escrow), we can use this innovation so sellers can maintain their own page of goods that can be updated.
Think something like Tor or Freenet but fast to load and encrypted. All these tools together enable a decentralised Silk Road. If the seller on the remote end is a robot, then you could communicate with the robots over p2p encrypted protocols to send messages and update the page (like a forum or Wiki). There's very many possibilities from this tech. I especially like using the blockchain as an authority for human usable names for identities and cipherweb locations.
btw maybe you should pay to people when you retrieve the file. therefore depending on how fast you want the file, you put up an auction and gather the bids, then a special transaction is created for atomically exchanging the file for your credit (as agreed by the bid).