I'll tell you the best tip I ever learned, one that has landed me many an interview, back during the 2001 recession - though I can't say it led me to any job offers, it worked every time for interviews.
Go research the company. Look on the About Us section for a list of the Team bios. If there is a VP of Marketing listing, read his/her bio. Do some more research on google. Find something - anything - that you might be able to use as an opening. Hint: VPs of marketing get quoted in the press all the time. They also speak often at industry events.
Then guess at the VP's email address (they are usually obvious - try first initial, last name, dot company dot com). And send an email directly to the VP. Bypass HR completely. Keep the email SHORT (VP's don't have a lot of time), informal, and have a hook.
For hooks, in the past I have:
- asked a VP if he is related to so-and-so that I went to college with, who has the same (highly unique) last name
- remarked about how I live on the marathon course and never miss it (to the VP who ran it and was interviewed in the press)
- referred to the VP's recent quote in an article that I found inspiring... this would work if the VP blogs too. Or has a powerpoint preso set up on that slideware site.
- appealed to our alma mater (if we went to the same school)
This hook catches their attention, and should be in the form of a question, so that they respond to you (and you then know they read your email).
Then show in your email that you have done your research and know something about the company, such as a recent product launch or other market success. What is in the news? (Check out their News page for recent press releases). You don't have to be an expert in their field - just show you did some research, and it intrigued you enough to want to know more. Throw in that you saw their job listing, and you are attaching your resume for consideration.
Total - about 3-5 lines, that's it. Don't go on and on about you. This is not your usual cover letter. Make it about the individual, and his company.
Attach your resume.
Every time I've done this, the VP has responded - usually to answer my hook question. I'll get a simple, pleasant one-line reply back. And they copy HR. HR immediately takes notice, and calls me. (I have had only one HR person get a bit pissed at me for doing this... the rest all thought it was creative).
I also know an admin assistant who did this exact same technique - she had the balls to email a high-profile CEO of a very large, multinational corporation. I didn't even know such CEOs actually read their own email. But, it landed her a job. Personally, I suspect this works particularly well with smaller companies, and targeting the VP of the department you want to work for. And, I'm guessing it probably works best for marketing and sales positions - because these fields really like ballsy people.
I would also add that you should search the company on LinkedIn first. If you have any sort of connection through your network to anyone at the company, get an intro. But even if you don't, you can intro yourself to someone within marketing.
And if you never get a reply, send in through standard channels as well. Likely, your email just got lost in a sea of other stuff.