travelinsured.com
travelguard.com

If travel is purchased with a credit card, most cards provide some travel insurance coverage. Check with your bank for details.

Look into CSA Travel Insurance. I heard they have a good reputation, but confirm that.

When I booked my flight I was offered insurance with Allianz. I went ahead and bought it, because there is a 10 day period for me to review the policy, and I can cancel and get a full refund.

Just to say that if medical evacuation is one of your reasons for buying travel insurance, you need to check very carefully to see just what you're getting. Many travel insurance policies say something like "arrange for medical evacuation", which means they make the arrangements but don't cover the cost of the actual evac flight. This is something to examine closely and possibly ask the insurer to be sure just what you're getting.

I used CSA Travel Insurance a few years ago when we booked a vacation property on the Gulf Coast, worried that the September date was in the midst of hurricane season. Sure enough, Hurricane Isaac hit a week before we were supposed to arrive and badly damaged the property. We had a very good experience with CSA. The communication was great and we received a full refund on the cost of the rental, which was our only pre-paid cost since we were planning to drive there, not fly.