The Intensive Care Unit: not just a node, but also my workplace. In the ICU you will see pretty much every nasty thing that can potentially be done to a human body, with the possible exception of certain specialized species of pornography.
The ICU is, in my opinion, a sort of hospital limbo. You're not dead yet, but you're sure as hell not out of the woods, either. In fact, in the surgical ICU (SICU) in my hospital at San Antonio, odds are about 60 percent in favor of death. Not great Vegas odds, there. We see and treat anything from traumatic amputation (arms or legs ripped off) to massive head injuries (have you ever touched somebody's head and felt it 'squish'? You don't want to. Trust me.) to impalation of various objects into the body. That's why mom tells you not to run with those scissors.
You may have picked up on the fact that there is more than one 'flavor' of ICU. There is also the MICU: the medical ICU, generally for patients with chronic deteriorating illnesses, or acute onset illnesses that need to be stabalized. The NICU, the neonatal ICU, is both the most rewarding and the most heartbreaking experience I've ever had. You get to take care of newborns fresh out of the oven, many of whom simply reqire close monitoring for a few days. In the meantime, you get to cuddle and bottle-feed them, and then send them home. Get your baby fix with none of the nine months of waiting! The flip side, of course, is that you sometimes have to watch babies die. That's why I'm not going back.
Anyway, an ICU is sort of a relative term. It depends on what kind of care your hospital is able to give, and then sorts your most critical patients into its ICU. For example, I've worked primarily in Army hospitals in major cities (San Antonio and Seattle). However, I'm currently at an Army Combat Support Hospital (CSH or CASH, not MASH anymore) in northern Iraq (Yes of course we have internet access. What are we, savages?). While we see far more explosive injuries, gunshot wounds and traumatic amputations than we would in the US, most patients that survive as far as the OR will generally get better. This is because our OR is much more limited than a large hospital's would be, and are therefore unable to sustain the lives of the most critical patients. What's the upshot of all of this? Just to illustrate that an ICU is a hospital-relative term, as well as a repository for seriously ill patients and highly skilled nurses. And yes, I did just resist the temptation to pat myself on the back.