 Adium
Adium is open source instant messaging for Mac OS X. All of the most widely use protocols are supported such as AIM, ICQ, .MAC, MSN, Jabber and more - even Novell Groupwise and Lotus Sametime are... Read more aMSN 0.96
aMSN is an open source clone of MSN Messenger. It aims to implement as many features as possible from the original, and to provide even more features on top of that. Alot of the extra features are... Read more Ekiga 3.2
Although people are still using the telephone in one form or another as the main means of communication, VoIP (Voice Over Internet Protocol) is the newest form of voice communication.
Ekiga,... Read more Emesene 1.0.1
Emesene is a MSN Messenger clone, which primary goal is to support all features of the Windows Live Messenger Network (WLM). However, it does have a few extra features - besides trying to be... Read more Evolution
Evolution is an e-mail client built from scratch to be an alternative to Outlook on Linux. Today it has evolved beyond that - and provides stable functionaly through typical e-mail features. But... Read more FrostWire 4.18
FrostWire is an alternative peer-to-peer file sharing service on the Gnutella network that is modeled after LimeWire and in fact, derived its code from LimeWire Pro. You'll find it a bit different... Read more HydraIRC 0.3
Hydra IRC, an open source chat client, is quickly gaining a stellar reputation. Internet Relay Chat (IRC) used to be only for the computer literate but Hydra makes it easy for anyone to enjoy it. ... Read more Miranda IM
Small and fast are only two positive things that come to mind when trying to descripe Miranda IM. Like many of its open source "competitors" it is an multi-protocol instant messenger capable of... Read more Mozilla Thunderbird
This full-featured open source email client provides an excellent open source alternative to all commercial email clients. Thunderbird has a wide list of features of which some are: support for POP... Read more Open-Xchange 0.8
The Open-Xchange Collaboration and Integration Server Environment allows you to create, store and link appointments, contacts, tasks, email, bookmarks, documents, forums and many more elements and... Read more Pidgin 2.6
Pidgin is an instant messenger (IM) application that cover multiple protocols - including (but not limited to) AIM, ICQ, MSN, IRC, Jabber, Novell GroupWise Messenger and Lotus Sametime. These... Read more PlanetaMessenger.org 0.2
PlanetaMessenger.org is an open source universal Instant Messenger (IM) developed fully in Java. PlanetaMessenger.org has plug-in based support for the different IM networks. Among the supported... Read more Psi 0.10
Psi is an open source instant messenger client built for Jabber (the open source instant messaging protocol). However, to ensure that you don't loose touch we your friends who have not yet switched... Read more StarDict 3.0
StarDict is international dictionary software with more than 1000 dictionaries available. It features Glob-style pattern matching, scan selection word, fuzzy query and more to aid you in looking up... Read more WengoPhone 2.1
WengoPhone is an open source softphone for telephony over the internet also know as ip telephony and voip. It provides free PC-to-PC calls as well as chat and video conferencing. Through Wengo it... Read more XChat 2.8
XChat is an IRC (internet relay chat) client. IRC is a world wide chat systems that has existed since the 80s. Based on multiple networks of servers where each network lists it's own topics (aka... Read more Zimbra 5.0
Zimbra is an open source server and client technology for next-generation enterprise messaging and collaboration. Zimbra delivers innovation for both the administrator and the end-user as well as... Read more | 
AOL Instant Messenger (AIM) 5.9
Adium 
