Yeah... Here's an easy few...
Gold plated sockets that contact the tiny SIDES of the pins of the chip. Commonly found on Galaga boards. TI was one maker of this crap.
Silver plated steel pins on chips. Commonly found on Galaga, Pac Man, Galaxian, and other boards of that era. Not just related to PROMs but also found on TI 74xx logic chips too.
Ceramic substrates with soldered on pins in SIP format. If they bend in the slightest the pins and solder pads pop off and break contact. Commonly found as resistor packs on Pac Man, Super Pac Man, Ms Pac Man, and Galaga.
Leaking capacitors that eat traces. VERY well known for killing audio hybrid chips on many different Konami games including Simpson's Bowling, X-Men, Lethal Enforcers, and MANY others. Also found in early to mid 90s Ford airbag computers. I documented repairs on the Ford airbag computers found in the Mazda Miatas on the miata.net forums.
Solder plated edge connectors for power and/or pulling power at levels approaching the margins on edge connectors. Commonly results in burning traces and bent (from heat damage) pins on the edge connector. Atari and Midway/Namco were big culprits here.
Crappy capacitors that dry out or just simply stop working. SNK used them on many thousands of Neo Geo boards. Intel, Asus, and other manufacturers also got caught up in using those caps on PC motherboards... not to mention the thousands of TVs, monitors, and other devices with those inside.
RJ