MetroIRC!

HexChat is an IRC client based on XChat for Linux , but unlike XChat it’s completely free for both Windows and Unix-like systems.HexChat was originally called XChat-WDK which in turn was a successor of freakschat.

Facebook Messenger is a faster way to message. Reach friends right on their phones, get and send messages fast, message everyone at once and more.

Trillian is an instant messaging app that works on phones, tablets, and desktops while keeping your chats neatly synchronized between all of them! We think conversation should be easily shared between all of your devices, not trapped as text messages on your phone. Here's how we do it:• INSTANT MESSAGING: Your unique Trillian username can be used to send unlimited messages free of charge. Trillian uses your existing data plan and/or WiFi.• ANYWHERE: Trillian's continuous client feature delivers your chats instantly between all of your connected devices. In addition, Trillian automatically silences push notifications on mobile devices if you're active on a desktop - no more dealing with a phone buzzing on your desk all day!• SIMPLE: Trillian places a strong emphasis on fast and reliable message delivery and a beautiful, easy-to-use interface.• SECURE: All communication with Trillian servers uses TLS to ensure third-parties can't read your chats.• INTEROPERABLE: Of course, Trillian wouldn't be Trillian without support for Facebook Chat, MSN, Google Talk, AIM, ICQ, Yahoo!, and Jabber. »

Adium is a free and open source instant messaging application for Mac OS X, written using Mac OS Xs Cocoa API, released under the GNU GPL and developed by the Adium team. Based on the libpurple protocol library, Adium can connect you to any number of messaging accounts on any combination of supported messaging services and then chat with other people using those services.

ChatSecure is a free and open source messaging app that features OTR encryption over XMPP. You can connect to your existing accounts on Facebook or Google, create new accounts on public XMPP servers(including via Tor), or even connect to your own server for extra security.

Empathy is a messaging program which supports text, voice, video chat, and file transfers over many different protocols. You can tell it about your accounts on all those services and do all your chatting within one application.

Miranda IM is the smaller, faster, easier instant messenger with support for multiple protocols. Designed from the ground-up to be resource efficient while still providing a rich feature set, Miranda includes support for AIM, Jabber, ICQ, IRC, MSN, Yahoo, Gadu-Gadu and more. Additionally, with the choice of hundreds of plugins, icons, sounds and other content.

Miranda New Generation is a successor of a popular multi-protocol instant messaging client for Windows - Miranda IM . Very light on system resources and extremely fast.

Yahoo! Messenger is an instant messaging client developed by Yahoo! inc. for real-time communication of its users. It provides text chat, file transfer up to 2GB. conversations with audio and video, games. It also supports International Calling, Phone in Number and sending free SMS like Skype.

The goal of Gajim is to provide a full featured and easy to use Jabber client. Gajim works nicely with GNOME, but does not require it to run. It is released under the GNU General Public License.

Digsby is a multiprotocol IM client that lets you chat with all your friends on AIM, MSN, Yahoo, ICQ, Google Talk, and Jabber with one simple to manage buddy list. Its also a social networking tool that alerts you of events like new messages and gives you a live Newsfeed of what your friends are up to on Facebook, Twitter, MySpace and more.