Here is an ActionScript 3 function that will return intersection information between a segment and circle.
It's useful to me to know if a segment is partially intersecting with a circle or going completely through.

The intersection Point of two lines is useful to know. This is a function to find it in AS3.

Here is a scrolling background and keyboard control test for some AS3 classes I been working on. I used the image of superman from some sprite graphics I found on the web. The images for his flight positions are loaded dynamically. This is for allowing me to load other images for different characters without changing too much script.