EfexBASIC v1.0 by Mark Hanzen (1990) is a neat extension for Commodore 64 BASIC that adds a bunch of screen related commands that give you different effects like clearing the screen with a vertical swipe, or fading out the characters on the screen. All in all there are 12 new commands to make your BASIC program pop with a little flair. 

The help screen you see when first starting the extension is all you need to start using the new commands.