For all things photography I visit the following websites:
For Camera and Lens reviews
DPReview – the most comprehensive source of camera reviews along with sample images in RAW and JPEGs
Imaging Resource – another fantastic website with great reviews
Snapsort – for quick camera comparisons (a simple and clean design)
DXOMark – a website that strictly tests camera sensors and lenses.
The Luminous Landscape – the best website for medium format and large format systems, both film and digital
Ken Rockwell – My go-to-guy for advice relating to camera gear and photography. I’d listen to him.
Photo.net – A great forum with possibly every topic under the sun. You’ll find what you are looking for here.
For reviews and advice related to photography
KEH – probably the most trusted site when it comes to used equipment.
B&H Photo – the most well known and recognized brand selling all kinds of camera equipment
Adorama – another well known website that is on par with the above two.
Ebay – the first place one should check in, to know prices and trends.
JJ Mehta – if you are in India, the JJ Mehta forum is the place to look at when buying used gear.
To buy and sell equipment (New and Used)
APUG – The largest and most comprehensive website devoted entirely to photography on film
If you are shooting film
Ansel Adams’ three volumes: The Camera, The Negative and The Print – everything you’ll ever need.
The Art of Photography – An approach to personal expression by Bruce Barnbaum – if you need something more modern.
For anyone beginning out in photography or who needs a thorough refresher course, here are the books I recommend: