How do photographers get their colors so vibrant in photographs?

Is there a setting to boost color on your camera ( i have a nikon D90) or is it all editing? Because i know not all photos look that vibrant before editing.

I use Adobe Lightroom 2, but 3 is out now. It has controls to enhance all colors at once or selective colors. Like blue, to enhance sky backgrounds.
Other software is out there to enhance colors. Digital photos are enhanced and the old film process colors and other improvements are sometimes made by the company.

If you check the manual, it will give you information about boosting colours in-camera…

also, the use of filters can help with that… Particularly with ones such as polarising…

Most proffesionals, although it may not look like it, use editing software to bring out colour in their images. So the answer is editing.
However, there's also settings on some Cameras to boost colour, someone else said there are filters, and they are right you have filters to give the image a tint.