Google Talk is infact one of my favorite google services due to it’s variety of features and intergration to GMail. Even though Google Talk does provide simplicity in every way possible but one small problem still presists.

If you have ever used Google Talk, you should have noticed the lack of an option to choose font style, size or color. There is however a work-around which allows you to send bold or italicized messages in Google Talk.

To send a message in bold, you simply need to add asterisk (*) before and after the text.
For example: *Hello World* would look like Hello World

To send a message in italics, you need to add underscore before and after the text.
For Example: _Hello World_ would look like Hello World

If you prefer to send the message in both Bold and italicized style; add both underscore and asterisk before and after the text.
For Example: _*Hello World*_ would look like Hello World  

[Thanks Thilak]