Here in Texas, rohypnol, and its cousin rivetrol, are everywhere. Though quite illegal in the States, people smuggle them over the border from Mexican farmacias in lots of a few hundred, and sell them at a markup of five to ten times the price in Mexico. Lather, rinse, repeat.
Every punch bowl at every frat party here is laced with roofies, often with a subtle yet piquant mix of Everclear and sometimes codeine or vicodin. Calling this dangerous doesn't really cover it - if you drink enough, this mix is potentially very, very lethal. To Hoffman-LaRoche's credit, they've funded free testing through Student Health Services here, but that's pretty cold comfort that you only find out the day after the night before.
Of course, rohypnol's only use isn't as a date rape drug; it's a very powerful tranquilizer, and there will be always be people who take tranquilizers for fun. Most people I know that take the family of "roches" for recreation either take the pills straight or crush them up and smoke them with a bowl of weed. Of course, cultivating a serious downer habit is always dangerous, and rohypnol's ludicrously more powerful than, say, valium. While not (at least so far as I'm aware) physically addictive, users grow psychologically habituated fairly quickly, and to generalize grossly, the personality type that's attracted to tranquilizer abuse in the first place is generally inclined to take things to excess. Take too many roofies, with or without alcohol, and you put yourself at a serious risk for total respiratory arrest. To put things in layman's terms, you get so lazy that breathing just seems like too much trouble.
In response to break's writeup, I think that eradicating rohypnol from the world isn't really a solution. It just might be possible from a technical point of view, since rohypnol's a fairly complex synthetic drug, and can't just be refined from a plant, but it wouldn't really fix anything. People would use other drugs for date rape, like GHB, which can be synthesized in a kitchen with a few simple precursors, or the hoary old standby of alcohol, which isn't about to go away anytime soon. A better question to ask would be why our culture creates a situation where a significant minority of the young male population feels that getting laid by drugging a girl into insensibility is a fun way to spend a night out.