Best Performance Upgrades for Little Money - Here's My Vote

Low budget seems to mean a lot of different things to many people. I saw a story one day on how to build a low budget stroker motor. It was 5 grand. Maybe I'm just cheap, but I believe you don't have to spend a ton of money to improve performance and driveability. I'm fortunate enough to be within driving distance of at least 5 u-pullit yards, one of which still has great prices. My vote for the best cheap upgrade has to be electronic ignition. I pulled a distributor, wiring harness, and ignition module from a 74 or so Valiant. Total cost, $25. I saw a guy there one day pulling an electric fan setup off a Durango. He told me it would work perfect on his Road Runner, provided he get the wiring squared away. At $25, how could he lose. I also remember reading a story where a guy bought a flea market drill and a good grinding bit, and proceeded to port his own heads, removing all the bumps and ridges, and expanding the port a little. With gasket matching the ports, I think he said he only spent $30 total or so. So the question of the day is, what ultra cheap upgrades have you guys discovered that cheap mucks like myself would be interested in hearing about?