If you prefer to shoot your landscapes handheld, built-in image stabilization can be your friend. This feature compensates for handheld camera shake, letting you shoot 2 to 4 shutter speeds slower than you could normally handhold successfully. Sony's SLT-A99 is the only current full-frame DSLR with built-in sensor-shift stabilization, which works with any lens you mount on the camera. For other cameras, you can get lenses with built-in stabilizers: Canon's are labeled IS (image stabilizer), Nikon's VR (vibration reduction), Sigma's OS (optical stabilizer) and Tamron's VC (vibration compensation).
Many landscapes require great depth of field to get a nearby subject and more distant ones sharp. The depth-of-field preview stops the lens down to shooting aperture so you can see in the viewfinder just how much depth of field you have. However, stopping down makes the viewfinder image darker, which, in dim light, can make it hard to see anything. Some cameras offer depth-of-field preview in Live View mode, which maintains image brightness for easier evaluation.
Most of today's DSLRs can do high-resolution 1080p video, with sound. This gives the landscape shooter another way to present the subject. You can record the motion and sounds of waterfalls, surf and rapids, and winds, to accompany your high-quality still images.