At the end of 2005, 86,000 people were waiting for at least one organ. Only 14,154 people, living or dead, actually donated. 45,000 new people were added to the list that year.
The median time that a patient waits for a kidney transplant was 1,176 days as of 2001. Too small a percentage have gotten a transplant since 2002 to estimate the median waiting time in subsequent years. The story is similar for liver transplants, lung transplants, and heart-lung transplants.
For other transplants, the wait is shorter, but not the mere hours that House's patients seem to consistently swing.
Aside from the quibble about accuracy in fictional TV shows, this is a reminder to check the box on your driver's license, but more importantly, to talk to your family. That checkmark only matters if your family is willing to sign the papers when the doctors give them a chance. If you don't discuss exactly what you want them to do in that situation, you may well deprive someone else of a future.
And until then, give blood. It imposes essentially no cost on you, and can save up to three lives. You can give every 8 weeks, and demand often outpaces supply.