By "pester them" I don't mean firing endless e-mails to the same person in Recruitment.
As a hint: If anyone manages to bypass HR/Personnel Services, find out my name and designation and get his tidy two page CV onto my desk they're at least guaranteed an interview. After that they have the same chances as any other interviewee of getting the position, but showing initiative and a true interest in the job is always recognized.
Checking a website once month for a vacancy notice and then missing it on the vital day isn't showing initiative. Finding someone who works for the company concerned and using that contact to 'mine' for the right person to write to is.