You got a brand new Operating System for your Mac: Snow Leopard OSX or Others Old Mac OSX, and want to use Yahoo Messenger Official Client that works properly in there with more enhanced stability, you can try to use Yahoo Messenger for Mac 3.0 Beta.
Features in this version including Yahoo Insider that would make you faster to received local news, weather, mail notification and more.
Download Yahoo Messenger 3.0 Beta for Mac Installation File
You can download the file installer of YM 3.0 Beta for Mac (Snow Leopard Supported) here: …

To Reply any Incoming Message in your Google Talk Messenger Service, you may need to install and use GTalk Auto Reply. This GTalk Application would help you to answer or response any incoming message automatically with the text message that you have to add before.
Download Google Talk Auto Reply Software | Source Code
License: Open Source / Free
Website: gtalkautoreply.codeplex.com
Installation

Download the gtalk auto response software and run setup.exe
Use your gtalk account with its password to login and set the auto reply message that you want.
Done

Yamee is one of Mobile Chat Client of Yahoo Messenger works for most Mobile Phone base on Java J2ME. Yamee works for Nokia at least for these Version: Nokia 2630, Nokia 2865, Nokia 3155 (CDMA), Nokia 3250, Nokia 3230, Nokia 5300, Nokia 6233, Nokia 6235 (CDMA), Nokia 6280, Nokia 6300, Nokia 6600 black, Nokia 6630, Nokia 7210, Nokia E61, Nokia N70. Yamee for Siemens S65 and for Sony Ericsson it works for version Sony Ericsson K300i, Sony Ericsson K508i, Sony Ericsson K510i, Sony Ericsson K550i, Sony Ericsson K610i, Sony Ericsson …