Do you know there is another category of power conversion technology called "Switched Capacitor (SC)" power supply? In SC technology power conversion is achieved by charging and discharging capacitors. There is no magnetic component involved in the operation. Because there is no inductor needed for power conversion, the SC technology makes it possible for IC designers to design the whole converter in one chip (introducing capacitance to IC is easy while incorporating an inductor to IC is difficult). Below is a controller newly released by TI for SC LDO. However this controller still needs the capacitor to be designed to the outside of the chip. Since the ceramic caps become smaller and smaller, such SC converter can be very small. Copy and paste the link to see more details.

TPS7A78 – AC/DC conversion, magnetics-free. This switched-cap LDO can take standard AC in, and output 1V-5V @ 120mA with surprising efficiency, about 75%. It also has very low standby power. Take a look at the datasheet for how in the world this part can do that.

http://www.ti.com/lit/ds/symlink/tps7a78.pdf