PhoneBook 3G

I have been toying with idea of developing a phonebook application for sometime now. Here is what I think:

Location/Time-Zone Aware PhoneBook: Whenever I travel, I try to connect with people I know from that city. Contacts/PhoneBook app on my phone has address field as well, but there is no way to search contacts by city, country etc. I think if we can search our contacts by city, it will make things a lot easier.

Sometime before calling somebody I need to figure out their time because they are in different time-zone. If somehow I can see the time for a contact based on his time time-zone, then it will be easier to decide when to call him.

If we integrate PhoneBook with GPS/Maps, we can see our contacts on map and may even see contacts near your current location. There are apps which show your nearby friends on map, but haven't found any app which is integrated with your phonebook. Similarly city name stored with the contacts can be used to automatically derive time-zone and show user's time.  I just wonder why our inbuilt phonebook/contacts on mobiles don't support this already?

Other Possibilities:

I think this new PhoneBook can have enormous scope. It can be integrated with SocialNetworking sites like LinkedIn, FaceBook, Orkut etc so that your PhoneBook shows profile photos, updates from these sites as well. Some companies have already started doing this. PhoneBook 2.0 and INQ1 come to my mind immediately, though there are others as well.

I miss one more thing in the current PhoneBook, which is search contacts by their profession/company. I may know many lawyers, doctors but when I need one, I can't think of somebody immediately, so if phonebook contains company/profession info about my contacts and allow me to look-up all doctors or lawyers when needed, it will be cool.

PhoneBook is most basic but very helpful application on any mobile phone, but its probably being overlooked by most mobile handset/software companies. I think complete overhauling of existing PhoneBook application is required and RIM, Apple, Microsoft and Google can do a huge favour to all the mobile users by replacing existing PhoneBook apps in their respective mobile OS by what I would like to call PhoneBook 3G.