[bigben2k]

I opted to use the negative voltage rails from the first power supply; it's a waste of effort otherwise.

As for status lights, every PSU has a number of output lines that you can tap into. Namely:
Power_Good (aka power_ok); will be high (TTL output level, 5 volts) when all the voltage rails are in spec. A simple LED and resistor will allow you to monitor that line.

I opted to adapt pHaestus' circuit, to indicate that each PSU is receiving AC. Alternatively, you can use the +5 sb (standby), which is always on (as long as there's power, and the PSU is switched on, if there's a switch).

Note that I haven't completed this project yet, but there is a thread on this in here... somewhere.