The following is a selection on other links related to graphviz.
Haskell has a very active IRC channel on the Freenode network. The attitude is very friendly and willing to help you with any queries or problems (just don’t be surprised if the denizens suddenly start discussing technical ways of cleverly solving a very simple problem!).
A few other Haskell libraries provide bindings for Graphviz (with differing degrees of support; e.g. they may require you to manually enter in an attribute’s name rather than using a pre-defined list).
language-dot: developed concurrently with graphviz’s
29188.8.131.52 release (which is when it underwent a large rewrite to use the new printing and parsing classes, etc.; before that the printing and parsing support in graphviz were really, really bad), this takes a rather simplistic approach in representing, printing and parsing Dot code.
dotgen: allows you to take a monadic approach to writing Dot graphs.
flow2dot: generates sequence diagrams from textual descriptions; uses an internal fork of
FGL: contains a module that lets you create very simple visualisations from its own graphs.
prof2dot: generates Dot graphs based upon profiling information.
This is a list of other Haskell packages that you may find of interest.
FGL: The Functional Graph Library is the de-facto standard graph library for Haskell. graphviz provides several functions using FGL-style graphs.
SourceGraph uses graphviz to visualise static call graphs generated from Haskell software (via the Graphalyze library) and is the main driving force behind the development of graphviz. Sample visualisations are also available.
vacuum: extracts and visualises heap values of Haskell programs. By default uses its own internal Dot graph generator.
pandoc: used to create this website.
The main Graphviz page is full of documentation and also contains a gallery of sample visualisations which are helpful in picking up ideas on how to best visualise your data. Most Linux distributions will have packages, and installers for Microsoft Windows and Mac OSX are also available for download.
Various other programming languages also have support for a Graphviz; a non-exhaustive (as for starters graphviz isn’t listed there!) list is available here.