Scripts/Programming
Yes, you can add javascripting, Flash or any other client-side scripting. You cannot add PHP, ASP, ASP.NET or any other type of server-side scripting.
When working with a custom page or User Control that has scripts in it, it's best not to switch between Design View and HTML view on the text editor for the page/control.
Keep in mind that you can really screw your site up with some poorly programmed javascript, so be careful! I will help out with code whenever I can, but it's really an un-supported feature as I cannot guarentee the quality of code being added.
