X-Pidgin is another great Free Portable Instant Messenger Client (based on Pidgin) offered by winPenPack. Pidgin is instant messaging software that enables you to be logged into a variety of chat networks simultaneously.
aMSN Portable is a free MSN Messenger clone based purely on aMSN with a portable wrapper. This Portable IM enables you to chat, display pictures, have conferences or video chat with all your MSN contacts while on the move.
Coccinella is a cross platform Portable Instant Messenger or Portable IM with a built in whiteboard that incorporates the following features. Secured connections, avatars and emoticons, plugins, open standard instant messaging, multi user chat (group chat) and file transfers.
Miranda is another great Portable Instant Messenger application. Like Pidgin, it supports AIM, ICQ, IRC, MSN and Jabber, however, Miranda also sports a plugin system that allows you to include other popular instant messaging protocols like Gadu-Gadu, Netsend, Skype, Yahoo and more.
Pidgin Portable is Portable Instant Messaging software that allows users to have access to all of his or her Instant Messaging accounts from one simple to use application. This portable instant messaging application is based on the popular Open Source Pidgin IM software.
PixaMSN is a neat little portable MSN Messenger Clone. Unlike MSN Messenger, PixaMSN writes no files to your hard disk or registry so it can be stored and run completely from a portable device such as a USB flash drive.
Gaim Portable is an Open Source portable instant messaging client application. It is essentially an all in one instant messaging client that allows you to take your IM settings and buddy lists with you wherever you go on a portable device.