Probably the largest internet based community for photographers out there.
Requires registration, not really for the casual user.
Digital Photography Review
Incredibly through reviews and a big forum to boot.
By the sometimes controversial Michael H. Reichmann.
Another of those really through review sites.
Another usefull site for reviews.
Great articles, take a look at the Canon Flash Photography. Its like the bible.
Nice site with a incredible amount of links for various photography related things.
Other Photography Pages
Schildt - Fine Art Photography
Unconventional, this is a must see.
Great photography site, mostly nature in its various forms.
Custom Hyperfocal Distance Chart
Photoshop Tech Vault 2.0