Hi, Mark,
Welcome to the forum. If you do a search using "travel insurance" or "health insurance" as your search terms, you'll find lots of threads with information.
The bottom line, I think, is that there is no one easy answer. I bought insurance two years ago with medex, and then learned that the coverage was probably not all that it was cracked up to be. So this year I just didn't worry about it, probably a bad idea but fortunately I was ok.
Your age and the type of coverage you want will make a big difference -- do you want medical coverage or does your insurance cover overseas treatment? The first thing to do is to find out exactly what your insurance policy and your credit card will cover. Then -- Do you just need emergency care? Do you want evacuation and coverage for "repatriation of remains?" You have to be careful with the policy language, because as I wrote in one of those older posts, when a friend went looking for a policy, he learned that for one company, "arranging for evacuation" meant "making the phone call to find a company who will evacuate" and not "paying the cost of medical evacuation."
I know there have been good recommendations for World Nomads, so maybe that's a place to start. Good luck and come back with more questions once you get a feel for what's out there.
Buen camino, Laurie