Omnigraph Sketcher (Omni Group) is an application which can help you make clear, precise graphs that can be embedded in any document. A few of my Economics students trialled the product last year and then decided to purchase a license. ($19.95, less for bulk purchases, free 14 day trial available) It is a useful tool for students completing an Extended Essay and as shown below it can draw complex models and parabolas clearly. Other than using drawing tools in a word processing application, I haven’t come across many tools to draw good graphs. Any further ideas welcome.