This binder has some good resources on Poison Oak.  It is interesting how you get more sensitive to it over time.  I struggle with it quite often.  Technu is my weapon of choice.

Take a close look at this plant on the right and avoid it at all costs!  It is a vine, so you will find it winding its way up trees or along the ground.  The leaves are grouped in threes and it turns fabulous colors in the fall.