What an excellent idea for a thread!
Short story: Oakfield, WI F5 on either July 18 or 19, 1996. (I know, I know, how can I not know the date for sure?)
Details: I have always been a weather geek all my life. Love anything extreme, big storms, big heat, big cold, big snow. It's all good to me. Always listened obsessively to the SKYWARN nets when they'd get activated for southern Wisconsin. But it had never really occurred to me to go out and look for the mesos. Besides that, we have so few in Wis. (and they're usually just little spin-ups) and in our immediate area, the visibility was usually terrible.
By the early 90's I was hearing about this Stormtrack magazine. By the mid 90's, I was aware that some people went out and actually chased tornadoes and I got some videos. (The Tornado Project series)
The day of the Oakfield tornado, I knew a red box had come out. I had a few ham repeaters up on the scanners, but it was still just hot, humid and sunny. My wife was beat from gardening and suggested a run for some ice cream. I'm always up for that. We drove and got the goods, and I brought the scanner along.
Leaving Hartford, WI, I heard about a tor warning 2 counties north and west of us. I usually dismissed these things, but when I started hearing persistent reports of a tor on the ground, my awareness sharpened. We got to a place where we could look quite a ways to the north and OMG!!! I had NEVER seen a storm like this in Wisconsin! (And I was already 32 at the time).
It was just a flat-out classic supercell. Huge, sculpted, surrounded by bright sunny skies. My eyes bulged out of my head. 70,80% of Wisconsin storms are grungy, squall-line type pieces of shat. Midwestern folk know what I mean.
Eyes glazed over, I looked at my wife. We've been together a long time and anyone who knows me knows I turn goofy around big weather. Normal people have been amazingly tolerant of me.

I told her what I had been hearing in my earphone and even she was very impressed with this supercell. I said, "We gotta get a closer look at this storm!"
We busted north up Highway 41/45. The storm was moving just south of east, well north of us. It was a dream intercept for a newbie. Because of terrain, we could never see the base until we got about 5 miles away. At this time, I wasn't entirely up to speed with where tornadoes formed in storms and such. As we traveled north, I kept hearing more and more reports of damage. This was not a brief spin-up. I was nervous, so I kept pulling off on overpasses, well shy of the actual base. Finally I got to the Hwy 67 off ramp and it was fairly dark by now. We saw cars parked on the bridge and knew we had hit paydirt.
As we got to the bridge, we saw a thin rope snaking back up into the clouds. We saw the last minute or so of what had been a 30-minute (don't quote me) tornado. Later, we understood that it had done it's worst damage in the town of Oakfield, (about 15 miles west/southwest of Fond Du Lac) I did manage to calm down long enough to try chasing a bit farther east, in case it produced again. If it did, we didn't see it and we headed back home (about 30 miles south)
I didn't see my 2nd one until 1999, on June 4 or 5, with Cloud 9, near Bassett, NE. I grew into chasing slowly. I'm not a risk taker at all, and the whole chasing thing just intimidated me, even tho I was definitely drawn to it.
Now I've had easily the best month of my chase life (this May). I realize that's no huge accomplishment, given all the nearly sure-fire systems there have been, but still, I'm very proud of finally getting to where I am.
Without Oakfield, though, I don't know if I would have had that extra kick in the pants to get going. (If anyone wants more info on the Oakfield, WI F5, please search for veteran Wisconsin chaser Don Lloyd's website. He was *all* over this storm from start to finish)