Today I discovered #Quicksy. It's a spin-off of the #XMPP app "Conversations(.)im", developed by the same people, but designed with ease of use in mind. It actually links with and uses your phone number to sign in so it's easy to on-board new users, and easy for new users to find people in their contacts list that already use it. But, it is just a standard XMPP client, so it is still capable of communicating back and forth with people on other XMPP / #Jabber servers.
QuicksyQuicksyA spin-off of the popular Jabber/XMPP client Conversations with automatic contact discovery. Sign up with your phone number and Quicksy will automatically—based on the phone numbers in your address book—suggest possible contacts to you.