IDEs and Development environments
ErlIDE
ErlIDE is a plugin for Eclipse with projects and modules wizards, syntax highlighting, code indentation, OTP documentation, auto-completion, shortcuts to function declarations, bracket matching, build management, support for different runtimes, compiling, access to the Erlang shell, debugger, etc.
Distel: Distributed Emacs Lisp
Distel extends Emacs Lisp with Erlang-style processes and message passing, and the Erlang distribution protocol. With this you can write Emacs Lisp processes and have them communicate with normal Erlang processes in real nodes. This makes it easy to write convenient Emacs user-interfaces to Erlang programs.
Has support for dynamic tags (jumping to the source of a function), a debugger, interactive Erlang sessions, process lists, code profiler, etc.