I think the best solution is using 78xx and if you need fixed current, put a resistor to limit current in lower voltage, like 5V or 3V, and reduce dissipation.
If you cascade the regulators you'll have a Power regulator to 12V, for example, becouse it 'll supply the current for all the others bellow it. Use regulator in parallel, not in cascate.
To produce fractional voltages or a varialvel one use LM317 and a Pot or insert diodes between Pin2 of 78xx and ground. Each diode increase a 78xx from closelly 0,7V.
Good Look and don't forget to use a 100nF cap as GrandAlf told you.
If use diodes to elevate voltage, cap is a must.
Regards,
Renato