On the World-Wide Web, there are several URLs of likely interest:
GHC Developers Home (developer documentation, wiki, and bug tracker)
We run the following mailing lists about GHC. We encourage you to join, as you feel is appropriate.
This list is for GHC users to chat among themselves. If you have a specific question about GHC, please check the FAQ first.
http://www.haskell.org/mailman/listinfo/glasgow-haskell-users.
The hardcore GHC developers hang out here.
There are several other haskell and GHC-related mailing
lists served by www.haskell.org. Go to http://www.haskell.org/mailman/listinfo/
for the full list.
Some Haskell-related discussion also takes place in the
Usenet newsgroup comp.lang.functional.