Georg Lukas
Bruno the Jabber Bear (XMPP)
FreeBruno is the cutest Jabber/XMPP Instant Messaging (IM) app available. It is a themed version of the open source yaxim app.
AndroidAPRSdroid - APRS Client
PaidAPRSdroid is an APRS application for Amateur Radio (HAM) operators.
Androidyaxim - XMPP/Jabber client
Freeyaxim (Yet Another XMPP Instant Messenger) is an XMPP client with a clean user interface and open source (GPLv2).
Android