The Graffiti Research Lab (GRL) invented the Throwie as an easily assembled and magnetically attached LED lamp to be tossed into public space in large numbers. We hacked their design with a small computer to send messages in morse code. post 
My son and I present the hacked throwie to the GRL team on Sunday morning.
I spoke about my work with Cybords at the first Maker Faire. I brought kits with small computers preprogrammed for various functions including tapping out morse code.
GRL was a hit at the event having repurposed an aging school bus as mobile headquarters for their hands-on construction of throwies. We met on Saturday when I bought one of their kits to make a dozen throwies of my own. At dawn on Sunday I was hacking parts from both kits to make a throwie that blinked morse code.
Throwie Talkies on exhibit at Ars Electronica 2006.
The trowie alone allowed the thrower to send the message: I was here. By adding the computer control a more complex, and admittedly obscure, message is added: I was here with a message. Can you hear it?
We kept in touch. When GRL went to the Ars Electronica show in 2006 they sought to bring a talking with them. I make four for them with various messages, the most reflective of the maker-graffiti culture was the text from the Wikipedia page on graffiti.