Boxes command is a text filter and a little known tool that can draw any kind of ASCII art box around its input text or code for fun and profit. You can quickly create email signatures, or create regional comments in any programming language. This command was intended to be used with the vim text editor, but can be tied to any text editor which supports filters, as well as from the command line as a standalone tool.
XPenguins is a program for animating cute cartoons animals in your root window. By default it will be penguins they drop in from the top of the screen, walk along the tops of your windows, up the side of your windows, levitate, skateboard, and do other similarly exciting things. Now you can send an army of cute little penguins to invade the screen of someone else on your network.
You can now enjoy mysteries of the sea from the safety of your own terminal using ASCIIQuarium. It is an aquarium/sea animation in ASCII art created using perl.