On the subject on ninjitsu "Chi powers:"
From the information I've gleaned, one of the bigger advantages ninjas had over samurai (aside from way more practical equipment and tactics centuries ahead of its time) wasn't that they had any sort of supernatural abilities, but that they were able to convince enemies that they did. Some would wear spiked cleats on their feet and hands, which allowed them to climb sheer walls, or catch incoming sword strikes. This would give them the illusion of having superhuman strength or agility. They are also said to have colored their clothing in red dye to mask the color of blood when they were cut, giving them the illusion of being invincible.
Such clever trickery could also lead to people's imaginations getting the better of them; if ninjas were capable of scaling walls without ropes, catching swords with their bare hands, and being struck without bleeding, what else could they do? So I'd have to guess that most of the stories of ninjas having any sort of supernatural powers were either carefully crafted illusions or simple urban legend.
(Though the CIA has been known to employ remote viewers and psychics, which does potentially validate the argument. Still, there's a difference between psychics and "Chi")
Also, regarding ninja clans roaming the Asian continent, there aren't any. Ninjitsu is still being practiced by many, but the last actual ninjas died off in the late ninteenth/early twentieth century, not long after the Samurai were wiped out. They had mainly served as bodyguards for the Shogun for the last century or so of their existence (to eliminate them as a "wild card" in the clashes between feudal lords), and when Japan began to modernize, there was simply no need for them. Since then, modern special ops groups have taken many of the ninjitsu techniques and adapted them for modern warfare. Simply put, ninjas were ahead of their time way back when, but now they're obsolete.
Chris Wallace said:
From what I've read, the ninja's specialty is stealth, long-range & sneak attacks, not direct combat. Their hand-to-hand was relatively poor, contrary to what the movies would have you believe.
Not true. Ninjas were more adept at disguise and mimickry, more focused on "hiding in plain sight" than sneaking around in the shadows. And if they were discovered, their method of combat was made specifically to exploit the weaknesses of the Samurai's technique, through confusing movements, hidden weapons, etc. In a straight confrontation between a ninja and a samurai, the ninja would more than likely win.
I could go on a whole rant about how ineffective the samurai really were and how the romanticized view of them is based mostly off of confrontations with other samurai instead of any sort of foreign or modernized opponent, but that's another argument for another day.