Editor Modes and Style Files
Haskell (literate style) mode for Vim, Haskell Mode for Emacs, Haskell mode for Nedit, Haskell mode for Vim, Hugs mode for Emacs, JCreator for Haskell
FAQs, Help, and Tutorials
Haskell Reference at Zvon, Haskell Tutorial, Haskell Tutorial, Haskell: The Craft of Functional Programming, Haskell: The Craft of Functional Programming, Monads for the Working Haskell Programmer, Online Bibliography of Haskell Research, The Lambda Complex
Implementations
Chameleon, Data Field Haskell, Distributed Haskell, Eden, Glasgow Parallel Haskell (GpH), Gofer, Haskell++, Helium, Hugs, Hugs Archive
Libraries
A Compiler Toolkit in Haskell, CGI Library, FranTk, Fudgets, Gtk+Haskell, Haggis, HaskellGnome, HaSQL Project, HGL Graphics Library, HOpenGL
Haskell API Search
Search engine for the Haskell standard libraries (Prelude, List, Array, etc). Search by function name, or type signature. Gives examples and overviews of many functions.
Haskell.org
Repository for information on the lazy functional programming language Haskell: Descriptions, documents, history, news, HaWiki, software (libraries, tools), humor, merchandise, and links.
Hello, World program
What Hello World in Haskell looks like.