http://mat.i2p/minecraft-scanning
I also set the server MOTD and player list to something enticing, with the hope that a random person with a scanner finds the server and tries to join. And it worked! At first, I was getting joins from bots with randomized names such as “WwMygQ” and “5PhFta3”, but after a bit I got my first griefer who fell for the honeypot.