Original shimano rapidfires (not plus). Lasted approximately 3 seconds before breaking, and then being exchanged for DX thumbies.
Alu anodized bolts - ok until people started using them to hold their front brakes on...
Girvin vector forks - had a set on my Proflex. Approx 3mm travel.
U-brakes - an excellent way of collecting leaves, and then your rear wheel jams solid.