I like that cone dealy. Between 1 and 1.7 liters per day isn't a lot, though. That's 2-4 Watercones per person to reach a gallon a day.
There is a technique called "solar water purification" that involves putting fairly clear water (as in not muddy) in a clear plastic bottle then leaving it on a reflective surface (correlated steel roofs are kind of the default) for a day. The UV from the sun kills parasites and microorganisms in the water. Very big in 3rd world nations.
A good-sized pocket magnifying glass, something with a 2" lens or better, is a fantastic fire starter. Of course, you have to start your fire before the sun goes down, but it works reliably and is non-consumable.
Those "space blankets" (the little Mylar survival blankets that come in a package about the size of a deck of cards) are phenomenal for regulating heat. Of course you can wrap up in one to stay warm, but you can also use one as an amazingly effective sun shade. Not only can it protect you from the sun, but it's bright as Hell and can be seen for miles.
Simple black jugs are an effective way to heat water for bathing. Many camping outfitters sell solar showers, black vinyl bags designed to be hung from trees.
Solar cigarette lighters are also decent fire starters. These are just small parabolas of polished metal that focus the sun's rays on a fixed point.
Photovoltaic battery chargers are good for keeping small electronics charged. Again, these are available at camping outfitters. You can use one to keep your cell phone or GPS operating, but they are woefully inadequate for anything more demanding, such as recharging a dead car battery.
As you may be able to tell, I've long been fascinated with making use of the sun's power! However, I am not one for throwing money at neat toys. I like the simple, the nearly-free.