Be Always Idle or Always Busy On Gtalk
Google Talk does not allow users to decide when their status changes to 'idle' and back. The result is that others can tell whether or not you're at your computer.
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)