Haskell.org:Repository for information on the lazy functional programming language Haskell: Descriptions, documents, history, news, HaWiki, software (libraries, tools), humor, merchandise, and links.
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 Programming Language: Growing article, with links to many related topics. [Wikipedia]
Hello, World Program: What Hello World in Haskell looks like.