No doubt there have been a lot of improvements and developments over the last 100 years that have helped the fly fisher. Here is my personal top 10 list.
10. The fly rods have improved... faster and better
9. The Internet This is a great tool for fly fishing research.
8. Breathable Waders... What did we do without them?
7. The SUV... We must get to the river in style.
6. The Leader Loop... OK, I admit it, I'm lazy and don't like knots.
5. Flip Focals... I'm going blind but don't want to admit it. Maybe that's why I don't like knots.
4. Sit on Top Kayaks... Great fly fishing craft.
3. Pocket Size Toilet Paper Rolls... When you gotta go...
2. FFF and TU
1. The Fly Line... I agree with Cliff and Cliff that the single improvement that has helped fly fishers the most is the upgraded fly line. No doubt!