This is not intended to be comprehensive or authoritative, just free online resources I've found valuable while learning more about Erlang.
- Learn You Some Erlang
- Erlang Handbook: A concise reference for Erlang
- Concurrent Programming in Erlang / Part 1 (PDF)
- Try Erlang (hands-on web-based demo)
- Erlang for C, C++ and Java Programmers (very short overview)
- Thinking in Erlang
- Joe Armstrong's Ph.D. thesis (PDF)
- Introduction to Erlang blog series
- The Architecture of Open Source Applications: Riak and Erlang/OTP
- Getting Started with Erlang User's Guide
- OTP Design Principles User's Guide
- Official Erlang docs
- Alternative presentation of Erlang docs
- Inside the Erlang VM with focus on SMP (PDF)
- Erlang: The Movie
- Erlang is not a Concurrent Functional Programming Language
- Systems that Run Forever Self-heal and Scale: Lambda Jam keynote by Joe Armstrong
- Erlang's Open Telecom Platform (OTP) Framework: QCon talk by Steve Vinoski
- Erlang – A survey of the language and its industrial applications (PostScript)
- Why Erlang Is Awesome
- When would you choose Erlang?
- Erlang's Big Idea
- Solving Embarrassingly Obvious Problems In Erlang
- More Embarrassingly Obvious Problems
- Programming Rules and Conventions (incomplete)
- Études for Erlang
- Erlang Programming Exercises
- Exercism (so far, Elixir is supported but not Erlang)
- Erjang (Erlang on the Java VM)
- I imagine (hope?) this will always be the only entry in this subsection
So far have only stumbled across Akka patterns, but there should be enough commonality for those to be useful.
- History of Erlang
- One Pass Real-Time Generational Mark-Sweep Garbage Collection (1995)
- The development of Erlang (PDF)
- Implementing a functional language for highly parallel real time application (PostScript)
- Erlang - A survey of the language and its industrial applications (1996)
- An Introduction to Core Erlang (PostScript)
- Bjarne Däcker's thesis (2000)
- Actor Model of Computation: Scalable Robust Information Systems / Hewitt, 2012 (PDF)
- The Actor Model (video)
- Actors and Continuous Functionals / Hewitt & Baker, 1977 (PDF)
- A Universal Modular ACTOR Formalism for Artificial Intelligence / Hewitt, Bishop, Steiger, 1973 (PDF)
- Actor-Oriented Models for Codesign (PDF)
- ACTORS: A Model of Concurrent Computation in Distributed Systems / Agha, 1985
- Relation to Pi Calculus from
erlang-questions - Modeling Erlang in the Pi–Calculus (PDF)
- π-calculus (Wikipedia)
- Erlang Cookbook: collaborative code snippets at ErlangCentral
- Mostly Erlang (podcast)
- Erlang interviews and resources
- Akka team blog
- Why Do Computers Stop and What Can Be Done About It? / Gray, 1985 (PDF)
- Erlang on reSRC.io : List of free online resources
Twitter seems to be the de facto water cooler for technical conversations, and Erlang is no exception.
There are far more active accounts than I can comfortably list here; these are just a few of the more interesting ones.