Charting Library for iPhone iPad iOS SDK

Core-Plot Framework as simple as download and run

So your looking to add charts and graphs to your iPhone/iPad app.
There are a few libraries available here is one that seems to work fine for me

Core-Plot Framework
http://code.google.com/p/core-plot/

Here are two articles that show how to get it working, I chose the second.
http://www.switchonthecode.com/tutorials/using-core-plot-in-an-iphone-ap...
http://www.quickprogrammer.com/articles/pie-chart-drawing-in-iphone-usin...

There is also a nice sample app in the download.

-Enjoy