This is one of the best Contact Manager in the App store. You can easily create groups and subgroups as you like and edit them. You can set names and pictures or logos for each group/subgroup. never been easier than this to add or remove contacts from group/subgroups.
For instance you can add a work group and then add company names as subgroups. Now add your contacts on those companies from your address book. Very easy & convenient to use and organize your contact list.