I recently read about a sailing catamaran crossing from Ecuador to Easter Island. Not too far into the passage their autopilot failed beyond repair and they had no backup. The sailors then rigged what I call the "Chepo- Bungee2000 auto pilot". Basically a pair of Bungees rigged to the sheets and wheel. They sailed roughly 1800 miles on this system. On my little Precision 165 I use the single bungee system (Chepo-Bungee1000) tied to the tiller. It works well enough to leave the tiller for several minutes ;D . Sometimes simple is best.
I've seen a number of self-steering arrangement diagrams like that Brian, that use some form of interaction between sheets and tiller/wheel, but I've never tried it. Another thing I'm curious about are windvane systems, which I've also not seen in person. I've been meaning to do some studying up on how they work.
When going out solo, some type of self steering is necessary, even if it is not perfect. With the bungee set up, I have enough time to cut the engine and raise the sails. I try to head for dead upwind, but even if I am close hauled the bungee setup gives me time to leave the tiller. It gives me a break for a two handed lunch, or a minute to relieve the bladder after two cups of coffee. On some days which are "drifters" I can set the tiller and sit on the bow relaxing or hang my legs over the side, or fiddle with the sail trim. Best of all, no battery, cheap, replacement parts always handy.
Agreed, there's definitely something to be said for simplicity. I do like the auto tiller, but I still have the tiller clutch for backup. And there are some situations where I'll just pop the clutch on quick if I need two hands free for a few seconds. Also, I use the clutch for going hove to.
I have installed a Tiller Clutch on my new-to-me P15K. I've also found that the pure bungee method works surprisingly well.