The UBContacts app provides a simple to use way of keeping your own private set of personal contacts. The key to a contact is the name of the person. For each person there is a free text where you can input other attributes, e.g. names of children, events related to the person, where they live etc.
A search and a sort capability allow you to quickly fins the person and to review the related text.
By using iCloud as a backup and a possibility to sync the DB with other users you can maintain a common base of contacts across family members or other close friends.