Continuing on with what has turned into ASCII Sunday here at TUAW, a comment from Micah Cooper led me to FIGlet, which has been around roughly since the dinosaurs roamed the earth. It allows you to to create large ASCII-based text using various fonts and styles. After Micah reminded me about it, I Googled around and found a Dashboard widget based on the venerable Figlet (not to be confused with the venerable Bede or my personal iPod, which is also named Figlet).
You can download Figlet Widget (say that 5 times fast) from Apple's Dashboard widget site. It allows you to enter text and choose from 18 different text-based styles. You can then cut the text art from the results field, paste it into your favorite email program and annoy all your friends. Who could ask for more?