those that I can remember and without having to search the net are:
www.nikon.com
www.canon.com
www.minolta.com
www.bythom.com
www.epson.com
(notice that most of these website are the product names ending with .com, thus for someone who has never visited their website before, they can still guess by typing:
www.xxxxxxx.com, xxxxxxx=name of product)
Those good website I can't remember the exact address are (need bookmarks):
1. Moose peterson website
2. B&H website
3. Clubsnaps (if it is .com instead of .org, then it would be easier to guess for newbies)
If I were to register a domain, I will use my name, or my nickname that's easy to remember.