Change Nickname & Status Message in Google Talk
You can’t change your nickname in a way that other people will see it change as every nickname in the Google Talk contact list is the part before @gmail.com (but only the alphabetical characters are used) or the name you chosen for your GMail account.
To change the nickname
Go to your Gmail account and change the name there.
Choose Settings, Accounts, and then Edit infoformaton.
Click on the second radio button, and enter the name you wish to use.
All your emails will now have that nick as well as there is no way to seperate the two.
You can add a website in your custom message, clickable when someone opens a conversation with you.