If you have a history of losing or mixing up phone numbers perhaps these app could be useful
The MeContacts app offers you the options to create a widget for quicker access contacts, group SMS and exported and imported data. Lastly you can customize your choices.
This app makes sharing with people extremely simple. Pick what you want to send, hold your phones and gently bump your hands with another user and your data has been shared. You can share everything from photos, apps and contacts
Groupy / contact by group
This app manages your contacts by groups. You can Google sync, call and log, set specific ringtones to specific groups, mail and texts. You can also do a voice search, set backgrounds, along with sorting by last name, or several different accounts. You can also create shortcuts to groups and contacts.
Contact Analyzer 2
This app gives features to analyze and optimize contacts. This also allows you to manage your contacts information, delete duplicates of numbers, texts and email.