I keep the name and contact info relatively small - they don't care about your name and you lose real estate.
Then put what you are looking for: experienced sys admin looking for voip lead role in a technically challenging environment. (they need to know what you want, and what you are.)
I then put a list of skills:
servers: Windows 2000 through 2008-R2, CentOS, Ubuntu (I don't put nt, 2000, 2003, 2k3R2 2008, 2008-R2)... They should know. If you are going into a large org that will be indexing your resume then list all of them. Leave the linux distributions, I think it's more important to list each one.
languages/scripting: c++, python, perl, c#, powershell, bash
network: cisco, etc..
Then I put top 3 achievements (Career Highlights)
- Saved company x 2.3 million over 3 years by fixing the interwebs and filtering junk email.
- Successfully planned and integrated fortune 500 acquisition ahead of schedule.
That's what they are looking for first, in my experience. Do NOT make them read through your experience to figure out what the heck it is you do. They might go through a stack of 20 at a time and they don't have time to waste. They will biff you if you waste their time.
Put a few lines of info about each past job. Make sure to put symbols like $ and % which will draw their eye. Look at a page of text, your eyes will be drawn to symbols. Figure out a way to quantify something. "Reduced system deployment time by 80% by scripting install via powershell and vbscript."
A manager thinks in numbers and dollars saved. Let them think that you do too. :)
I always seem to get an interview now that my resume is formatted like that.