Agile Messenger - most famous and user friendly all-in-one application for your mobile phone
Eqo - cool one with great facilities save up to 95% on calls, 70% on text messaging, integrates all of MSN, Yahoo!, GTalk, AIM, ICQ, and Jabber.
fring - use it as an IM client, but also for free calls over Wi-Fi, GPRS or EDGE
IM+ - All-in-One Mobile Messenger that works on any mobile device
OctroTalk - keeps you connected with your buddies, and works seamlessly over GPRS/EDGE/CDMA/Wifi/Bluetooth data connections
QuickIM - connect to public MSN networks using your cell phone with one time license fee
JiveTalk - connect simultaneously to AIM, MSN, Yahoo!, Google Talk, ICQ, and Jabber
Causerie - an easily configurable chat tool with simple-to-use user interface that work on Palm, Blackberry, Pocket PC, Symbian and J2ME enabled phones.
TipicME - J2ME-based Jabber client that is really well done and absolutely free
MT Messenger - exchange messages using the most popular IM applications from MSN, Yahoo! and AOL
EpyxMobile - call all over the world from your mobile phone for SkypeOut tariffs
GoTalkMobile - Java application for J2ME enabled phones, allows you connect to Google Talk and Jabber
iSkoot - mobile application that allows you to connect by GPRS, 3G or Wifi and to speak or chat with all your contacts on Skype
MovaMessenger - a free mobile IM client, works with MSN, Yahoo, AIM, ICQ, and GTalk
Turbo MSN - a mobile MSN client for Nokia and Panasonic
Nimbuzz - call your IM buddies on their mobile or on their PC, chat with your IM buddies for free and send text messages for free.
Heysan - web based mobile messenger, compatible with most of the mobile phones including iPhone.
YehBA Mobile IM - allows you chat with your friends anywhere in the world, meet new friends across the globe through chat rooms, and have access to an unlimited number of fun services.
Palringo Vocal IM - transforms your mobile device into a walkie-talkie: communicate with a contact or a group at the touch of a buttonMSN Mobile - take MSN with you
Mundu - conference with your contacts across IM services in a single chat session