I have not yet thought about the order of importance but here is my list -- warning some items decidedly on list and some off :
1) paralelogram derailleur
2) T.V. coverage culminating in start to finish coverage on cable T.V. which has sparked world wide interest (especially in U.S.)
3) Drugs and methodologies that increase red blood count to include EPO and blood loading techniques where riders periodically inject their own blood to accomplish the same thing without risk of detection.
4) Team radios which have altered tactics completely.
5) clipless pedals (1984 is the first successful marketing of such but not the first invention of such)
6) early 80's invention of the polystyrene helmet to take the place of the hairnet. (probably saved a few lives - perhaps my own too)
7) double butted tubing (I still can't believe such a thing is possible to manufacture - what a marvelous technological improvement that was.)
8) modern nutrition drinks and foods (these were first seen in the seventies with Bob Hoffman and Joe Weider products I believe)
9) screen printed cycling jerseys that greatly increased available advertising square footage.
10) Cycling specific movies like "Breaking Away" and "American Fliers" which have inspired hoards of cyclists, immortalized the Masi and launched Specialized bicycles.
Garth Libre in Miami Fl USA