This is one of the most frequently asked questions at UMUC:
What can active duty military personnel do to prepare for their upcoming transition to the civilian workforce?
In helping UMUC students, I refer them to someone who specializes in the military-to-civilian transition. Because of UMUC's unique relationship with the military, the Career Services folks do a bang-up job with this: http://www.umuc.edu/careerservices/careerservices.shtml
All separating military members should be made aware of TAP: the government's Transition Assistance Program: http://www.dodtransportal.dod.mil/dav/lsnmedia/LSN/dodtransportal
This is an outstanding site and the one I recommend beginning with.
If a student Googles "military to civilian career transition," (without the quotes) most of the major sites will come up:
Monster.com runs http://www.military.com and offers Monster.com types of services, including lots of free stuff in their "Transition Center"--http://transition.military.com/reg/transition_center_registration.do