If you are a gtalk user, every time you need to chat with some of your friend you may search that person with his/her name in the search box in google talk desktop edition as shown in the image below.
But some times it becomes difficult to search and locate a contact which has some freak names with some unusual characters. In order to prevent confusion, you can better rename the frequently accessed contacts for chatting.
In order to rename a contact used for chatting, you just need to right click on contact and select the option to rename the contact, assign a easy name to contact with which you can remember as shown in the image below.
Once you have renamed the contact, you can search it any time with the new name and this will also get reflected in your gmail contacts.