What's your greatest tool find ?

What tool or device have you discoverd , maybe new on the market in the last 10 to 15 years that has made your life easier? Mine is a portable jump starter. I call it my "jump pack". I own 6 + acres and mow around 5 of it. In the past if I developed a flat tire or the battery wouldn't start on my garden tractor which I use to mow my lawn, I would have to drive one of my vehicles over to where I was broken down on the property and either jump start the tractor, or use my portable air pump hooked into the cigarette lighter of the vehicle to reinflate a tire. Now I just pull out the jump pack and quickly jump the battery, or hook up the portable air pump to the outlet built into the jump pack to pump up a tire. It has definitely made my life easier, as well as a couple of times I needed to use it to jump start one of my vehicle batteries.

Experience. Definetly the most important tool when it comes to wrenching on cars. If i knew back when i owned my RX-7's what i know now, man I could have saved a lot of money and hassle.

old ass thread but seeing as it isn't locked i am happy to say i just found a perfectly working timing light.

perfect timing as i was on my way to buy another one (mine broke a week ago)