One of the things I was most impressed with in Star Wars Saga Edition, aside from the keep it simple and straightfoward (KISS) design approach, was how they had handled saving throws. Third edition of the world's most popular roleplaying game condensed the numerous saving throws of editions past into three main categories, Fortitude, Reflex and Will. SAGA, and later 4E took this a step forward by turning Fort/Ref/Will into static defenses much like armor class. SAGA actually omitted a defense stat, instead it was absorbed into reflex so that your reflex defense was pinnacle in dodging blaster bolts and lightsabers alike.
I liked the approach, it made saving throws something other than "roll well or suffer some nasty consequence" as well as integrated them further into basic gameplay elements. Want to wave your hand and mind trick someone? Beat their will defense. Want to knock someone over or put them in a headlock? Beat their Fort defense. This was a world simpler than the inherent complexity of grappling rules and touch attacks. Most importantly by featuring them as static defenses it sped up combat by eliminating an entire side of rolling. This intrigued me the most as my combats were getting slower or more drawn out each session.
I adopted this approach into my game. It worked quite well, combat went much faster and the players enjoyed how straight forward it was. However, there was a growing discontent that we had trouble understanding or even explaining. Turns out it was simple. We liked rolling saving throws. We liked the suspense of whether or not the roll would mean life or death (or mind control, don't forget the mind control!) So saving throws reverted back to the way they were. In exchange defense was split in two to retain some of the variety of differing defenses. The two categories of defense are guard (think parrying and blocking with your shield) and dodge or getting out of the way.
Saving throws went through another big change but that's time for a later post.