jobfair - not much of choice.. only a few really company booth, other is headhunter

jobstreet - all my jobs i got from Jobstreet..
if u go direct to HR they wont look at it becoz they have too much to read and by going to jobstreet they can filter most out 1st before start reviewing..

Linked - so far did not apply anything but got a few invitation for interview by headhunter