what do you think is the best way to wear or carry something to clue EMT's into your medical facts, conditions, allergies, etc.?

Medic Alert bracelet or necklace.
http://www.medicalert.org/home/HomeCatalog.aspx?Catalog=Standard

A medic alert tag AND one of those pill fob holder things with the basics and a 24-hr source of complete info.

Or tattoo of all details inside both arms.

My friend's mother was going in for a mastectomy. The morning of the surgery, she went in and wrote on the good breast with a Sharpie marker: "Not this one, Stupid!" Afterward, the doctor said it was an excellent idea -- 'accidents' happen.

Sue

Best bet: Plain metal bracelet with prominent colored "medical" symbol (red or blue swiss cross, star of life or caduceus), that doesn't look like jewelry, worn on the left wrist (since most US pre-hospital IV's are started in the left arm, and American ambulance designs usually allow more working room on the patient's left side, it is more likely to be quickly noticed there).

All it really needs to contain is your main medical conditions or allergies, but the details should be in an easy to find location in your wallet or purse, usually immediately in front of or behind your driver's license, clearly labeled on the outside, on both sides, as "medical info" or some such, and not just some folded up scrap of paper.

A red dog tag is fairly noticeable, too, while also protecting your privacy. Sorry, but I won't be plugging any unknown usb drives into the ambulance's computer, although such a device can be tremendously useful to the patient in managing and documenting their own care.

Lastly, don't worry overmuch. The paramedics typically check things such as blood glucose routinely on any patient with altered mentation, and won't miss a diabetes related condition. Also, they should be able to recognize and effectively manage any life-threatening allergic or adverse reactions.

However, a cop or bystander might mistake a low-glucose diabetic for a drunk, or you may be in an area without advanced life support ambulance service, and, of course, the earlier we know about your condition, the better. So if you need a medical alert, wear it all the time, even at home. It does help.

Here's pretty much everything I want to know from every patient, beyond information about the current complaint:

Many prudent or experienced patients keep this information on their computer for easy updating, with printed copies to carry, give to family members, new doctors, etc. Be sure to include a "current as of __" date. I frakking love it when a patient or family member whips out one of these and hands it to me.

full legal name, and any aliases, former or nicknames that be used on older medical or insurance records
address, permanent and current temporary local for "snowbirds" and long term visitors
telephone number(s)
date of birth
SSN
emergency contact or legal guardian/health care surrogate name, address, telephone number
full name, address, and contact information of your primary care physician and key specialists
list of all current, recurrent or chronic medical conditions
list of all current or frequently used medications, including prescription, OTC and herbal (the latter two can be very significant)
list of all medical and food allergies or adverse reactions
list of all prior surgeries, hospitalizations and major illnesses or injuries
all medical insurance, Medicare or Medicaid information (photocopy of both sides of card preferred)
If incident is job related - name, address and contact phone number ofemployer and/or worker's comp carrier

That's funny

In pre-op for my last time under the knife, I had to sign my name to the arm they were to work on. They even required a family member as a witness,

Yep - you should see the happy looks when I used to bring Mom/Dad to the hospital, and handed them that, and the times I've had to go in, or go to a new MD, and I hand them the "The list"

Makes for a very happy triage nurse

RoadID.com. Mine's a Road ID Original in bright yellow. The interactive version with online database seemed a bit much for a guy with no medical issues.

Ditto everything Jeff said. In the list of info, a copy of the DNR or living will is good if you have one. Just saying "He's got a DNR" means jack-ship. No paper, no DNR. If you're needing this one, check your local regs. Some places need specific documents that are EMS approved, so a hospital form doesn't technically work if out of the hospital.

When I get old and decrepit, I'm getting "NO CODE" tatto'd down my sternum.

That's a Windows problem, not a USB issue.

The real problem is what kind of file is there, and what kind of reader is needed. I've billed many hours to clients who call and say "I was sent a FOO.XYZ file, how do I read it?". I've had to take apart files and extract data by hacking it out ($$$).

Even if Windows is banned from ER and ambulances to fix the security/virus problem, there's no way to expect anyone to know what to do with any material other than printed English text.

Thank Cthulhu I am not allergic to anything common, or I'd probably carry around a huge dog tag with NO PEANUTS scribbled into it.

As it is, it's just a flash drive listing ways to identify my (?) corpse, the fact I am allergy-free and a "return to" address.