Apps similar to Messenger for Desktop include Telegram, which has a free version. Other options are Element, Pidgin, Conversations and Adium. There's no shortage of Instant Messengers like Messenger for Desktop, with more than 50 alternatives for Windows, Linux, Mac, Android and iPhone.
BBM Enterprise enterprise messenger offers faster communication, collaboration and decision making while providing enhanced security over corporate data.
Canada
Swift is an elegant, secure, adaptable and intuitive XMPP client, with features that make it suitable for a wide range of use scenarios.
United Kingdom
GV Connect is an unofficial iPhone/iPod Touch application for Google Voice. It stores your account password securely in your device's keychain for faster logins - communication is done via secure connections (SSL) to the Google Voice servers and no contact information is...
United States
R&Q is a little instant messaging client for the ICQ protocol, fork of Rejetto's &RQ. It is simple, fast, takes a little more than 1 MB disk space and doesn't need setup.
Slick is a messenger application for mobile devices. It allows you to chat with your friends connected though various online messaging applications. Currently it is still in development, an alpha version
Slovakia
EU
AQQ is a Polish (but available in English) multiprotocol instant messenger with support of: AQQ, Jabber, Gadu-Gadu, Tlen and ICQ. It has many great features like: one tabbed message window for all conversations; quick search for contacts; file sending (even through FTP thanks to...
PolandEU
GermanyEU
Nettalk is a powerful but easy to use free (open source) IRC-client for Windows. The smart user interface is based on Windows standards, so it is easy to get used to it. The following languages for the interface are available: English, Spanish, Dutch, Russian, Chinese, Hungarian...
leafChat is an IRC client for Windows, Mac OS X, and Linux.
Chat with your friends using popular IRC networks. leafChat has a friendly, clean interface that doesn't get in the way of your conversations. Connect to multiple servers at once on the same screen, so that it'.
jsIRC is written using Socket.IO, node.js, jQuery Title Alert and Sencha ExtJS, relying on string.js, Lo-Dash and PhantomJS.
jakeIRC is a web-based Meteor IRC client that allows users to connect to their favorite IRC channels.
