ConsenSys's Medium blog on Ethereum, with explainers on smart contracts, UPort identity, IPFS and Bitcoin comparisons.
HN links it as an Ethereum learning resource, including a beginner smart contract intro and Vitalik Buterin's piece on UTXO versus account-based models.
Sadly not that much from the top of my head. I mostly became familiar with it through IPFS[0][1], but the Wikipedia article lists other projects that might have interesting resources[2].
Disclaimer: I'm working on a project[3] to create a content-addressable version of OWL2 (Web Ontology Language), so I'm certainly a bit biased.
[0]: https://arxiv.org/abs/1407.3561
[1]: https://medium.com/@ConsenSys/an-introduction-to-ipfs-9bba4860abd0
[2]: https://en.wikipedia.org/wiki/Content-addressable_storage#Open-source_implementations
[3]: https://github.com/rlay-project/rlay-ontology
Looking through the grandparent's twitter provides a couple links on their solution. https://www.youtube.com/watch?v=Tbe6WibeRzQ&feature=youtu.be and https://medium.com/@ConsenSys/uport-the-wallet-is-the-new-browser-b133a83fe73#.3y0hnukxn in particular.
Here's an article by Vitalik, explaining the differences between UTXOs and Ethereum's account-based model and why Ethereum did it that way.
https://medium.com/@ConsenSys/thoughts-on-utxo-by-vitalik-buterin-2bb782c67e53
Url changed from https://medium.com/@ConsenSys/farmshare-at-callicoon-ny-art-walk-this-saturday-12-8pm-3904b426d420, which points to this, which is more informative.
https://medium.com/@ConsenSys/programmable-blockchains-in-context-ethereum-s-future-cd8451eb421e#.6n4l0d7dh
https://medium.com/@ConsenSys/a-101-noob-intro-to-programming-smart-contracts-on-ethereum-695d15c1dab4