I just got finished adding 1,780 RTTY Art files to textfiles.com. RTTY stands for 'Radio Teletype' and was a method of sending text via Ham Radio (and other wireless means) around the world. (A lot more history is at the RTTY.COM site.)Link (Thanks, Jason!)
RTTY art was the use of BAUDOT code (uppercase only letters and punctuation) to create pictures. Sound familiar? If you've ever stumbled upon a large "ASCII Artwork" consisting of pinups, cartoon characters, or massive banners proclaiming "Merry Christmas", there's a good chance you've found an ASCII conversion of a RTTY art file, possibly from before microcomputers were sold.