If you are serious about your digital photography, you need a Digital SLR. SLR stands for “Single Lens Reflex” and these cameras offer the best quality and most flexible creativity options available to you in a camera. There are three levels of Digital SLR camera to consider. Each is basically separated by your budget considerations, and how serious you really want to be about your photography.
It’s widely accepted that (as of today’s offerings) the following cameras make the shortlist of best in breed:

Professional

  • Canon EOS 1Ds Mark II
  • Nikon D2X
  • Canon EOS 5D

Semi-professional

  • Nikon D200
  • Canon EOS 30D
  • Fujifilm S3 Pro
  • Olympus E-330

Hobbyist (entry level)

  • Sony Alpha 100
  • Nikon D70s
  • Canon EOS 350D
  • Pentax *ist DS2
  • Olympus E-500 Evolt
  • Nikon D50

With any of these cameras and a good lens (I recommend you buy the camera body alone, and choose a quality lens separately), you can create amazing shots, limited only by your imagination.
Your choice of camera body will subsequently limit you to a range of lenses, so choose wisely according to what types of lenses you may want to use. Having said that, most lens manufacturers make a full range of lens types. Once you spend money on a lens, you will keep it for life, so the camera manufacturer becomes one you stick with for a long time.
Another thing to consider is whether you want camera anti-shake technology built into the camera body, or whether you are happy to just buy a lens with this function built in. Dust protection is yet another technology that new cameras are beginning to include. Digital cameras are more exposed to electro-magnetic attraction of dust particles on the sensor than film cameras. This can result in dark spots on shots with a lot of sky.

In my opinion, the Canon 30D is the best value digital SLR available.

It’s an excellent combination of style, picture quality and value for money. You can pick it up from anywhere between $1950-$2250 if you shop well. The 30D excels at low-light photography, meaning you can shoot at much higher ISOs than other cameras, with far less digital noise in your resultant shots. This makes it a great choice for me with my live rock photography. It doesn’t include dust protection or anti-shake technology, but more than makes up for this by offering the very best quality a digital camera can offer. It uses a 1:1.6 ratio sensor, meaning that a lens focal length needs to be multiplied by this amount to get the true focal length. So, a 100mm lens is really a 160mm on this camera. This is great for zoom lenses, but not so good for wide-angle shots. If you plan to do a lot of landscape or commercial photography, then the next Canon in their range, the 5D, is possibly a better option as it has a 1:1 sensor. However it is a lot more expensive and doesn’t really offer any further improvement on the 30D.

The 30D has a popup flash. If you are serious about your photography you will use a dedicated flash unit, but there are times when you are taking snapshots and the onboard flash can be very useful.

For a very detailed review of the Canon 30D, as well as most other cameras on the market, check out Steve’s Digicams.