Line Breaks : Hold down shift and press enter to give a line break in the gtalk IM window. In this way you can write your message in multiple paragraphs.
Font Size : Hold down ctrl key and move your scroll button (mouse) up or down to change the font size in the message.
Bold Text : Use asterix before and after the text to make it bold. Like *hello* will make it hello.
Italic Text : Use underscores before and after the text to make it italic. Like _hello_ will make it hello.
Invitation Tips : You don’t need to say Yes or No when someone wants to add you as a friend, you can simply ignore it, the request will go away.
Do you know ?
A message in the google talk can be as long as 32767 characters long.
I’ll add some more tips and tricks on google talk as soon as they come my way.