Be Always Idle or Always Busy On Gtalk
gAlwaysIdle adds two new options to Google Talk, allowing you to change your status to be 'always idle' or 'never idle'. When your status is set to 'always idle', you'll appear idle to your Google Talk buddies, even if you're sitting at your computer typing e-mails and sending IMs.
System Requirements:
Google Talk Client Windows XP/Vista (no 64-bit operating systems)