When we made the first prototype I didn't find the PDF schematics for the Nucleo 64 boards.  We found that several of our pins didn't work for the desired purposes and we needed to rearrange busses using non-continuous pins. Fortunately this is easy with mbed, just probably bad for performance.  Well I have the PDF schematic now so here's some pointers:

Today I learned a schematic symbol for jumpers or at least solder bridges, that's what all the arc symbols are.

ADC pins:

PA_2 and PA_3 are used for the UART to the ST-Link(we already knew that, and the bridge is closed by default obviously, bridge SB_61 to connect the ADC Vref to AVDD on PA_3, closing SB_62 and 63 would connect these pins to the PA_2 and PA_3 pins on the header)

PA_4 and PA_5 are the DACS (we knew that too)

PB_1  connects to its pin by SB64 or alternatively to AVDD by SB65, to the pin is the default

That leaves PA_0, PA_1, PA_6, PA_7, PB_0, PC_0-PC_5

Digital Pins:

PA_13 is TMS (I guess JTAG Test Mode Select)

PA_14 is TCK (I guess JTAG test clock)

PB_3 is SWO (I guess JTAG Single Wire Output) 

PB_11 is connected to ground by a 4.7uf cap and apparently has no header pin

PB_12 is connected to the header by SB37 instead of AVDD by SB34

PB_13 14 and 15 are different pins on the F373 chip and there's a set of solder bridges that could be used to rewire this board for that chip

PC_13 is connected by SB17 to a pullup to VDD and Button USER to ground, which appears to have an RC circuit in parallel, probably to debounce.

PC_14 and PC_15 are connected to the 32768hz crystal

PH_0 and PH_1 can be connected to an 8mhz crystal across unpopulated R35 and R37 to achieve independence from the ST link which is usually providing it's own clock over PH_0, I don't know if PH_1 can be used for anything in the current config.

PD_2 seems to be an available pin somehow

PF_5 does not exist in this chip instead there is a VDD hookup through SB43, SB47 would connect it to a pin for chips that have it

PF_7 does not exist in this chip instead there is a VDD hookup SB31, SB30 would connect it to a pin for chips that have it.

So I know which pins not to use.