The Collaborative International Dictionary of English v.0.48:

go-getter \go-getter\ n.
   a person disposed to initiate action, rather than take
   instructions; an enterprising person; a person with a strong
   drive to accomplish useful goals; especially, one whose
   career progresses rapidly. [WordNet sense 1]

   Syn: whizz-kid, whiz-kid, ball of fire.
        [WordNet 1.5 +PJC]

WordNet (r) 3.0 (2006):

go-getter
    n 1: someone whose career progresses rapidly [syn: go-getter,
         whizz-kid, whiz-kid, ball of fire]