I've been recently starting work on an Ethereum client in Elixir. One of the goals of the project is to make the code clean and understandable. Looking through the repo could be good supplemental reading (for a different but similar blockchain). Also, we're always looking for new contributors.

[0] The Exthereum VM: https://github.com/exthereum/evm

[1] The Exthereum Blockchain: https://github.com/exthereum/blockchain