A couple ones I've read and found quite useful:

Make your contacts count

http://www.amazon.com/Make-Your-Contacts-Count-Networking/dp...

The science of influence

http://www.amazon.com/Science-Influence-Anyone-Minutes-Less-...

My two go-to books on the subject, very complementary to each other, are:

- The charisma myth: http://www.amazon.com/The-Charisma-Myth-Personal-Magnetism/d...

- Make your contacts count: http://www.amazon.com/Make-Your-Contacts-Count-Networking/dp...