Recruiting and Sourcing
This list may get broken up if it gets extensive but being from the recruiting/sourcing community there are a number of tools that are useful here for not only recruiters and sourcers but sales and business professionals. Have a tool you think should be added, be sure to let us know!
I have to say before I even tried it I knew Social List would be good based on one of it's main developers I have known for years well known sourcing expert, Irina Shamaeva. Social List pulls social list for recruiting, sales and marketing with highly targeted search agents they have developed.