Thierry Godfroy's home page, very complete QL related site,
with lot's of links to many other QL related sites, a lot of programs to download etc.
SMSQ/E home page, the official web site of the latest incarnation of a QL compatible OS. This site is maintained by Jochen Merz.
Dave Walker site : this s the place to look for the most recent version of c68, and there are also copies and/or links to related material. You can also find some libraries and programs which are developed by Dave.
Dead Letter Drop : the site by Jonathan Hudson. Contains all his software and the the stuff he ported to the QL etc.
Qbranch site : I assume he is the biggest QL dealer at the moment (well, nobody sells more of our stuff than they do). For all QL hardware and software, have a look here.
ClubQL : monthly QL related newsletter, aimed at the average user.
Chas Dillon software : this contains sources for some older packages like Turbo etc.