The simplest trick...The pen spins around the thumb

PENSPINNER

Step 1: Find the Center of the Gravity

The center of the gravity can be found easily...just by balancing the pen on a finger

Its Very good if the CoG (center Of Gravity) is in the same place as the CoP (Center Of Pen)

Step 2: Holding the Pen Right Way

Watch The Picture!!!

Step 3: The Spin!!!

Ive written numbers in the notes
EXAMPLE : IndexFinger :1 somewhere else on the hand 1
that means your gonna move your Index Finger to that place
hope you get it xD

Step 4: TRAINING!!!

YOU WILL NEVER EVER EVER EVER EVER and so on...

EVER be able to perform this trick without training!
i think ive written all the important!

NOTE : This took me a week to learn (and 2-3 months later i never drop the pen! :D)