The best i've found for a moderate amount of money is the MathType update for equation editor in word. It has pretty much anything you would ever need. 
It can be used with word or as a standalone program and has a free 30-day trial.
 http://www.dessci.com/en/products/mathtype/ 
		
		
		
		
		
			
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				"Empirically observed covariation is a necessary but not sufficient condition for causality" - Edward Tufte
			 
		
		
		
		
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