This page is devoted specifically to demo effects and tutorials on how to make demos. More general graphics coding is instead covered in the General VIC programming page.
To provide an example: Opening the border is commonly made in demo parts, but simply opening the border does not constitute a demo effect in itself (at least not during the last 20 years). Therefore you would find that on the General VIC programming page instead.
Many demo effects depend on precise timing. Therefore it might be useful to have a look on the Interrupts and Timing page.
The most classic demo effect, apart from scrolling text.
Those scrolling texts that we all hate to love that we love to hate. Also see the sprite section for a sprite scroller.