A couple problems that resist parallel algorithms:
	1.  Factorial
	2.  Fibonacci (can waste a lot of time in parallel)
	Commonality:  Each iteration depends on the previous

Interlude:  using a mutex:
	Brief explanation that I've given like a hundred times
	Now you know the last piece you might need
	Project 5:  atomic incrementation could be faster
		Maybe we better modify project 5!
	
How about an image one that's kinda in-between?
	How many objects are in nutsandbolts.jpg?
	Single-thread:  Use flood fill
	Parallel:	Cancel if we hit another thread's work
	Might end up needing a mutex (maybe)