There are a few.
the-leaky-cauldron.org
mugglenet.com
and even pottermore.com being among the most popular if you search on Google.
http://tinyurl.com/nxrn2q
There is a lot but the best one is the official warner bros one.
Harry Potter Fan Zone was created in 2003.
There are many places where one can see pictures of the werewolf from Harry Potter. The official movie website has pictures of the scene, along with fan sites.
There are no offical fan clubs but there are thousands of sites to do with it out there. Some of the biggest can be found in related links.
The queen of England is a fan of Harry Potter. She has had a Harry Potter themed party before. If you see pictures of the castle library you might find the whole Harry Potter series of books.
The Leaky Cauldron, MuggleNet, and Harry Potter Lexicon are my favorites. See the related links below. i go to Potterforums.com i am a member there so you can ask me anything about it
http://harrypotter.wbshop.com/ If you Google "Harry Potter shops" or "Harry Potter clothes/whatever" then results will come up with different sites, like that.
For a computer wallpaper, there are a number of sites that offer them for free. One such site is Fan Pop. They are available for download at these sites.
Very much, he is a great fan of Harry Potter.
Obviously you can still like Harry Potter. I guess that's what makes you a "fan".
Some good sites for Harry Potter news and entertainment are fansites like Mugglenet and Leaky Cauldron. The best site overall for Harry Potter is Pottermore, an official Harry Potter experience. It opens to all in October.