Sniffer for serial, i2C, SPI, onewire,
Already done, 4x serial signals, 1xi2c and 2xSPI, all in hardware. 1-wire not done because that's a software thing, therefore it can be done later.
RAM usage monitoring ...
Very intrusive, but could be done. I know this is a common issue. The monitor could fill blank RAM then test for the pattern later, finding the bottom of the stack is easy and AVRmon already does that, I just have to find out where the top of the heap is, maybe a quick 1-byte malloc.
Turn the Open Bench Logic Sniffer into a shield
Done, the plan is to make it a shield with all connections (except some user inputs) pre-wired.
Ability to interpret commands to and responses from slaves.
My AVRmon program already does that, I plan to incorporate it into this gadget.
A lot of the time, simple serial prints are all that is needed,
Handled in a couple of ways, you won't need the Arduino's hardware UART to print data to the screen.
being able to see the hardware bits flipping is sure handy at times
a tri-state/input mode test would be handy? Maybe pull a pin high/low with something like 0.5mA load, if it can wiggle it is not active output?
Hmm, I hadn't thought of that. I'll do so now
Thanks guys, it sounds like I'm on the right track so far.