With Google Talk being all the craze right now, some people hating it, and others loving it, I figured that I would post a list of tips and tricks for those curious about the extra "features" Google implemented and has not said much about...

Registry Tweaks

Tips & Tricks

• Wumpus Game : - First noted by a GoogleRumors commentor, if you add the buddy wumpus.game@gmail.com you can play the classic text-based game. Wumpus is an easter egg game that came with Google Talk (unfortunately, he didn't’t accept my invitation, so I can’t play).
• Change the font size - While holding the control key, move the scroll wheel on your mouse either up or down. This trick works while being focused in either the read or write area.
• Insert line breaks - If you want to have a message that spans multiple paragraphs, just hold shift and hit enter. You can add as many new lines as you want to create.
• Bold Text - To write something bold, you can use an asterisk before and after the word, like *this* .
• Italic Text - To use italics, use an underscore before an after the word, like _this_ .
• Switch windows - Hitting tab will cycle through open windows. It will select minimized conversations, to expand them just hit enter. If you just want to cycle through IM's and don't care about the buddy list, control-tab will do that and will automatically expand a minimized conversation if you settle on one.
• 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. (On the other hand, someone with whom you chat often will automatically turn to be your friend, unless you disable this in the options).
• Show Hyperlinks - You can show your homepage or blog URL simply by entering the it in your away message (at the top of the main window). It will automatically turn to a link visible to others.
• Google Talk Game - “Google Talk” also was the name of a word game which uses Google.
• A message can be 32767 characters long. 

How To

Conference Calls :

What you need to do to have conference calls: Open up a copy of Google Talk on all computers with which you wish to conference. After one copy is opened make a new shortcut for Google Talk but at the end of it add /nomutex. If you installed it to the default folder then your shortcut should read "C:\Program Files\Google\Google Talk\googletalk.exe" /nomutex. Open 2nd instances of the software on every user's computer. After this start a chain: User 1 should connect on one instance to user 2. User 2 will connect on his second instance to user 3. User 3 will connect using his second instance back to user 1. With this chain everyone is connected to everyone.

Nickname & Status Message :

http://chillapple.blogspot.com/2009/11/tips-and-tricks-about-google-talk.html

Contacts :

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. (On the other hand, someone with whom you chat often will automatically turn to be your friend, unless you disable this).
http://chillapple.blogspot.com/2009/11/tips-and-tricks-about-google-talk.html

Sound & Video :

It's possible to broadcast music, MP3, etc.. through Google Talk.
Unplug your microphone. Double click on the speaker icon in the lower right corner. This will open up "Volume Control". Select "Options" and then "Properties". Then check the button next to "Recording" then click OK. You may also have to change your setting under Mixer Device. Now the Recording Control screen should be up. On my computer I selected "Wave Out Mix". Click on the green phone in Google Talk and call your friend.

Keyboard Shortcuts

• Ctrl + E - It centralizes the selected text, or the current line.
• Ctrl + R - It justifies to the right the selected text, or the current line.
• Ctrl + L - It justifies to the left the selected text, or the current line.
• Ctrl + I - The same thing does that Tab.
• Tab - It is giving the area to each of the windows opened by Google Talk.
• Ctrl + Tab - The same thing does that Shift + Tab .
• Shift + Tab - The same thing does that Tab but in reverse.
• Ctrl + Shift + L -Switch between points, numbers, letters, capital letters, roman numbers and capital roman numbers
• Ctrl + 1 (KeyPad) - It does a simple space between the lines.
• Ctrl + 2 (KeyPad) - It does a double space between the lines.
• Ctrl + 5 (KeyPad) - A space does 1.5 between the lines.
• Ctrl + 1 (NumPad) - It goes at the end of the last line.
• Ctrl + 7 (NumPad) - It goes at the begin of the last line.
• Ctrl + F4 - It closes the current window.
• Alt + F4 - It closes the current window.
• Alt + Esc - It Minimize all the windows.
• Windows + ESC - Open Google Talk (if it's minimized, or in the tray)
• F9 - Open Gmail to send an email to the current contact.
• F11 - It initiates a telephonic call with your friend.
• F12 - It cancels a telephonic call.
• Esc - It closes the current window.

[HOWTO] Use multiple identities on Google Talk

Want to run Google Talk with multiple Gmail identities? If you have several Google Gmail accounts you also may want to run multiple instances of Google Talk This is especially important for families that share a single PC. Nothing worse than a family member signing you out so they can sign in under their own account!
Basically, to have "Google Polygamy" you need to run Google Talk with the following switch: /nomutex
Step 1: Right-click on the desktop
Step 2: Select New
Step 3: Select Shortcut
Step 4: Paste this into the text box:

Step 5: Click Next and choose a shortcut name such as Google Talk1, Google Talk2, or something related to your Gmail account for easy remembering which account is which.
Step 6: Click OK a few times.

[HOWTO] Use Google Talk via a Web Browser

You want to use Google Talk anywhere ? Follow these guidelines :)
Step 1: Opens your favorite web browser at the following address :
Step 2: Follow the instructions of the Page.
Step 3: You can talk with your friends

Google's Secret Command-Line Parameters

There are a few secret parameters you can add to Google Talk and make it function differently.
The most important, I think, is /nomutex, which allows you to run more than one instance of GT. Here are the others:
To add these, open up your GT shortcut, and where it says "Target:" add one or more of these inside the quotations, but after the .exe part.

Emotions :

All these emotions appears in color in a conversation : (but having them in an image would be better, like iChat or MSN)