For me I think the personal locator beacon (PLB) is stunning technology ... and costs folks under $300. It can bring rescue from anywhere in the world. Amazing.

Its your job to survive until that help arrives.

I also think GPS technology is pretty cool. I've read lots of stories of folks simply getting lost in the wilderness.

LEDs were mentioned. For me their benefit is as much their toughness. I clearly recall bringing my good incandescent light along camping and then one little drop ... and busted. Not sure why I never carried extra bulbs.

I'm not so sure this is survival, but I'm going to put a special thought in for modern coated nylon tents. I don't miss heavy damp mildewing canvas tents that you had to avoid touching while inside the tent to keep from starting a drip. Ugh!

Similar can be said for synthetic clothing and good synthetic insulation. Goodbye wool and cotton.

Really good stainless/semi-stainless knife steel is pretty nice stuff.