If you’re looking for Customer Relationship Management (CRM) and you use iPhone, VIPOrbit seems like a perfect solution for you.

http://www.viporbit.com/apps-iphone.html

The app gives you advance control over “orbits” (groups) and various operations to them. You can also add custom fields and more. PLUS, if you also have an iPad and/or Mac laptop, you can use apps customized for those platforms and sync everything. Either way, the iPhone app is free.