Off-the-Record (OTR) Messaging is an encrypted instant messaging protocol that automatically makes new keys throughout your chat session. To chat over OTR, both people chatting have to be using it. I use an instant messaging service called Jabber in conjunction with an OTR program called Adium (when I’m on a Mac) or Pidgin (when I’m running Tails). Micah Lee has written nice step-by-step instructions on how to install and use Jabber anonymously.
My contact info for OTR chat is: firstname.lastname@example.org