I shoot a lot of photos for publication, but am an editor so I choose a lot of photos for publication.
nwilliams had the best overall review of the subject. What most folks don't realize is that megapixels has little to do with resolution.
Internet resolution need never be higher than 72 dpi (dots per inch). Print resolution for newspaper type paper tops out at about 150 dpi because of the quality of the paper. Most full-color glossy publications don't go above 300 dpi.
When taking pix of things like NBA games you get a radio transmitter that fits in the hot shoe of your camera and it triggers house lights. All your upper end sports venues offer these to the pro photogs that cover them.
I shoot with a lot of cameras. My favorite is a Nikon D80, but I also shoot film and point-and-shoot digitals. Kind of like a gun, you choose what fits the task.
Best pic I ever took was with a cheap digital holding it two feet above my head and breaking every rule of photography I ever heard. It just worked.
I have one key judgment about a digital camera. That is how long it takes from the time you hit the shutter release until the shutter releases. Kind of like lock time.
I would offer this, digitals are much more difficult to learn to shoot well than film, but they are also much more versatile. They have many more settings that must be learned, but they can do things you'll never be able to with film.
The most important thing about taking a good photo, though, is knowing when you are looking at a good photo.
When I first started out I shot five 36-exposure rolls of everything. I'd just hope a few would be usable.
Friday I shot two frames and told them I was done.
My advice to a non-photographer is buy a point-and-shoot 5 megs or better and shoot lots of pix.
For a photographer who expects to sell his work, get a Nikon D80 or higher. I prefer the Nikon D200, but unless you are ready to cut loose with $10,000 for the camera body and lenses you may want to look at other options.
