Resumes simply refuse to go away. Despite the fact that there are so many other ways (like blogs and personal websites) to become visible that are so much more fun and interesting than old fashioned resumes, hiring managers, search firms and human resources just keep on asking for them.
It's really no mystery. Resumes are an excellent way to screen candidates, to get a glimpse of how they communicate, how well they write, their attention to detail, their level of self-awareness, and their ability to be concise and clear in limited space. When I was a hiring manager I received a constant supply of resumes, and I had the overflowing filing cabinets to prove it. There are all sorts of estimates of how little time readers spend looking at resumes... my initial read was typically about 30 seconds. In the old days, I sorted resumes into three stacks: yes, no, and maybe. Today, the 'maybe' stack has disappeared and the 'yes' stack can be pretty slim.
As a hiring manager, I was tough when it came to reading resumes. I grew up at the company that taught the world the value of the one-page memo: if you couldn't express yourself in a concise and persuasive fashion on one page, you had better re-think the proposition. I dissected resumes, looking for things that did not 'hang together', made no sense, contradicted previous sections, were too cocky or too wishy-washy, and worst of all, that made it pretty clear the sender had just tossed her resume into an envelope without so much as a note demonstrating she knew anything about our company or the open position.
I'm not necessarily a fan of numerous multiple versions of resumes - writing one good versison is difficult enough - but I am a huge fan of well thought out, highly targeted cover letters/emails. You may have heard that 50% of cover letters don't get read, but since we'll never know which 50% that actually is, it's prudent to produce the best cover letter you possibly can. Use a well written cover letter to distinguish your effort in key areas. Convince me that you are the best candidate. Prove to me that your skills and achievements are transferable to the role. Stand out from the other resumes languishing in my unread emails by proving you expended time and effort researching my company. Give me a reason to invite you in for an interview.
Your resume is your story. Make it worth reading. Yes, I like two page resumes, but if there are three really interesting and pertinent pages, I will read them. I look for outcomes, for results, both quantitative and qualitative. I look for proof statements that support the summary, and if there are none, I wonder why you chose the words you did for the summary. I try to picture you in the company, in the department, and in the role. If your resume convinces me that you have the skills we need (or you can learn them) and it telegraphs that you always delivered what you were paid to do at consistently high levels; if your cover letter shows me that you already have skin in the game; and if there is more than a glimmer that you may be a 'fit', there is a pretty good chance you'll be called for an interview. If your resume doesn't pass muster, regardless of the fact that you may be qualified, the likelihood of being selected for an interview is low.
Resumes are here to stay. Certainly they are moving from hard copy to electronic, from static to dynamic, from email to YouTube, from the written word to the visual, but you still need them, and they had better be compelling.