Someone finally getting close on this one. I’ve been saying for a while that it would be great if a bluetooth headset could clip in/out of a mobile phone to avoid worrying about where to keep it (other than hanging like a pendant or on an ear).
This is the closest I’ve seen, though it’s not clear which phones, if any, are ready to accept this headset. This device has a whole other angle: it can be charged in a notebook PCMCIA/ExpressCard slot – great for VOIP use and storage – though it’s not clear if it sticks out when inserted.
Colinizer 
To do a reverse mobile phone lookup you need to use a trusted directory service. While there is no national cell phone directory available in the USA due to various privacy concerns, there are specialized directories used by private detectives, journalists and anyone from suspicious spouses to bounty hunters to help in their business. These companies invest a lot of time and financial resources in compiling mobile phone numbers into huge data sets by using both private and public sources, as well as major cell phone carrier restricted databases.