Renaming address books
From MozillaZine Knowledge Base
The user interface in Thunderbird does not allow you to change the names of the two default address books, named "Personal Address Book" and "Collected Addresses". However, you can change either name by inserting the appropriate line shown below into the user.js file. Replace <New Name> with the name that you want to use.
To rename the Personal Address Book, add this line to user.js:
user_pref("ldap_2.servers.pab.description", "<New Name>");
To rename Collected Addresses, add this line to user.js:
user_pref("ldap_2.servers.history.description", "<New Name>");
For example, inserting the following line into user.js will change the name of the "Personal Address Book" to "All Contacts":
user_pref("ldap_2.servers.pab.description", "All Contacts");