Active Directory Phonebook is a great intranet add-on. Use this script to search Active Directory for users, locations, phone numbers. Much easier than having to maintain two databases for phone numbers. Quick and easy to install, just enter your company's info, account info and upload.
A2z - Web-based address book is a simple and efficient web-based contact management software that runs on PHP and MySQL.You can use it to replace your phonebook or even use it as an office-wide phone directory. It is all yours to decide!