Hi Bob, thank you... I was actually looking for something that would just mate with the freedom board...and have a blank prototyping area in the middle.. With absolutely no frills..
I ended up buying an arduino wireless shield ( http://arduino.cc/en/Main/ArduinoWirelessShield ) out of desperation since it has an xbee port and a micro sd slot which fit my needs for the most part for my first project with this board... Had I designed this board, I would place the parts in order to maximize space... I would also make the board match the footprint of the freedom board....I'm not sure if the freedom is supposed to be on top, or bottom....to me, it makes sense for it to be on the bottom since there's really no need for access to it (save the led and touch sensor - which I don't plan on using really and aren't entirely practical if you plan on putting this in an enclosure)...
Ultimately, for this project I am adding an oled display ( http://www.seeedstudio.com/depot/grove-oled-display-12864-p-781.html?cPath=163_167 ) , bluetooth module ( https://www.sparkfun.com/products/10823 ), wifly ( https://www.sparkfun.com/products/10822 ) , and a gps ( https://www.sparkfun.com/products/11571 )... Ultimately I will also incorporate a bmp085, HIH-4030, TMP102, ADMP401 MEMS Microphone, HMC5883L, HMC6352, TEMT6000, and finally when I get all that going I might add a Synapse RF266PC1 to pull data from another device... I've built another mbed based device with these sensors and the wifly with no bluetooth or display... works great..and all crammed onto a 3x4 proto board..
I always see boards with something already added.. For the Freedom, I'd say a blank - no frills proto board would be great... Maybe the addition of a micro SD card since the freedom doesn't have any storage like the mbed...but placed nicely leaving plenty of other room for more stuff...not in the middle of the board like you typically see..
If I were designing one for the mbed, I'd do pretty much the same... a spot for the mbed, ethernet and maybe a usb connector..no sd... But that's just me... =)
Edit: Oh yea... and for the freedom, it might be nice to bring up the pins that aren't on the arduino shields.... I'm not familiar enough with the freedom yet, but would both rows of pins be more useful? Also PTE1, PTE0 and maybe SDA_PTD5 which aren't on the arduino board... And why not mention this.... If you place the arduino shield on top of the freedom, a nice cutout for the reset switch looks like it'd be handy since there's a slight chance (depending on how close you place it) of the reset button getting pressed...
Thanks so much Bob!! You're replies have been a great help, and I look forward to hearing what you think.... =)
Is it just me, or has anyone else noticed that J1 and J2 are spaced just a tiny bit too far and will not fit into a prototype board with standard 0.1" holes? Am I crazy, or is this some arduino thing?