If you tap the inventory key as fast as you can while airborn on your karkinos, it will glide almost forever.
Over long distances it'll almost be faster than a rock drake as it keeps on building up speed using this trick.
If you're carrying a tamed Doedicurus in your claw the Doedic will automatically start harvesting any stones you hover him over. Just start pumping points into your Doedic's weight because it will stop at about half of its own carry weight. I've yet to discover another tame it will work with though...