Clean Up Your Address Book With Contacts Cleaner

"Anyone using a computer is likely to use some form of address book and if you're on a Mac, it's likely to be Apple's Address Book application. Initially it contains nicely organized contacts but after years of use it becomes filled with duplicates, messed up fields or duplicated details within the contact itself."

My address book is in dire need of something like this. It's available in the App Store for $4.99 USD, and has gotten good reviews. There are some quirks according to the review, namely thinking duplicates are there when they have already been fixed at times, but this is fixed by restarting the program. Worth a look if you need some help cleaning out your address book.