Most Haskell tutorials on the web use a style of teaching akin to language reference manuals. They show you the syntax of the language, a few language constructs, then tell you to create a few simple functions at the interactive prompt. The "hard stuff" of how to write a functioning, useful program is left to the end, or omitted entirely. This tutorial takes a different approach.
This is Learn You a Haskell, the funkiest way to learn Haskell, which is the best functional programming language around. You may have heard of it. This guide is meant for people who have programmed already, but have yet to try functional programming.
Hoogle is a Haskell API search engine, which allows you to search many standard Haskell libraries by either function name, or by approximate type signature.
Hackage is the Haskell community's central package archive of open source software. Package authors use it to publish their libraries and programs while other Haskell programmers use tools like cabal-install to download and install packages (or people get the packages via their distro).