As much as I like looking at them, I'd like to leave out the cars that get built with a credit card IE: shop cars.
I being married with kids/house/bills etc haven't really built anything in a while, but have built a few decent runners over the years. Of the vehicle I currently have, I'm seriously considering rebuilding my old orange truck. It was my dad's work truck, I drove it all through school, and bought it from him after I got out of the Air Force. It's a total rust bucket, and wouldn't really be worth restoring except for the sentimental value. The cab of the truck is going to be the hardest part to fix if I ever start on it.

The first car I ever modified was a 68 Camaro I bought for $300 in High School. It had a 3 on the tree, and a 250cu inline six when I bought it. No AC, but even better, no rust!
I went through several motor and trans combos, until the last I had in it was a 468ci big block, Doug Nash 5 speed overdrive, and 2.73:1 rear gears. I sold it in 86 (iirc) for $5,000. I wish to heck I still had it!
First car I ever put nitrous on was a 73 Challenger. The previous owner had put in a 340ci six pack with a slapstick, and a friend and I rigged nitrous to the middle carb. I couldn't tell you what jets were in it, but I remember you had to hold a red PB switch in your hand to activate the Nitrous when we first did it. Then I switched to a throttle linkage micro switch, and that was the end of that car.
I had been out street racing one evening, came home, and left the bottle on. I parked behind my dad's truck, so he got in the car to go to the store. When he left the neighborhood, (according to him) he floored it (just to check it out, not knowing about the nitrous, and first time he'd driven the car) He said it spun around on him twice. He drove it back home and told me "Boy, I don't know what the hell you've done to that car, but you're selling it RIGHT NOW!"

I never really modded my 99 Z28, other than some intake/exhaust stuff. I did run nitrous on it for awhile (125shot) but, mortgages, kids, etc kinda put the ole kibosh on the hot rodding.