Warning - George Dillman and his students are not taken seriously by expert Kareteka (see recent thread on e-budo.com)
Pressure points are often talked up, but as pointed out on the above thread, are useless if you can't get to the point of applying them.
A hyped up aggressor will ignore pain from a pressure point (or even from a nasty wrist lock - ask any police officer).
From an anatomical point of view IMHO pressure points fall into 5 categories
1. Flat edges of bone eg shins, ribs and arguably yonkyu in the wrist. Painful but not crippling
2. Deep muscles - such as the forearm, biceps or thigh - no flasher than the dead leg or charley horse you gave each other at school
3. Nerves - eg the lateral peroneal nerve as it wraps around the neck of the fibula. British police have been whacking this for over a hundred years to cause foot drop and prevent a criminal running away. Other examples would be the brachial plexus where striking the big nerves can cause a paralysis of the arm.
4. Very sensitive areas with lots of nerve endings such as the testicles, the bridge of the nose (so painful they can be crippling)
5. Genuinely vulnerable anatomical targets - the carotid plexus in the neck (used by doctors to slow heart rates dramatically), the so-called "solar plexus" which happens to be where you can hit the stomach, the pancreas, the liver and the aorta in one spot (unsuprisingly painful and dangerous), the temporal bone which is very thin and has a large artery running along it and is therefore a genuine "lethal target"
6. My favourite - knockout punches - head shots which jar the brain. These are Dillman's "knock out pressure points". Really a sharp tap on the jaw or the back of the head which any boxer could tell you about.
You don't need any fancy martial art training or special angles to hit these with good effect.