I'm just finishing up my first custom Arduino board. Once the bootloader is on I plan on connecting the smaller mono OLED display found on ebay or the larger color 4DSystems type. It features a 1A LDO regulator and two pushbuttons. Not much else since it's onlt 1.1" X 1.0" in size. Feel free to let me know if I missed something on the schematic. I tried to figure out what pins go where from the official arduino board schematics. Either OLED will push onto the front and the GPS will have to be sticky taped to the rear. On top of the regulator. The idea and code I used is at: Res Publica Non Dominetur – カルマン » Blog Archive » GPS Toy / On board computer
It's been about a year since this first post and i'm still working on the project! Since then pretty much everything has changed except the size of the display. I like the 32u4 microcontroller with built in USB, liPo battery charger and navigation button i'm using now. Check out the latest version at: https://sites.google.com/site/0miker0/arduino-sensor-board
The ICSP pads did originally plate though but as the board got more and more parts I realized that it took up way too much space on the opposite side of the board. I'm trying out pogo pins soon but for now I solder on a 6X2 header, program the bootloader and then de-solder it. It's a pain but frees up the entire backside of the board for tracks and components.
This link: https://sites.google.com/site/0miker0/ shows two boards i'm working on that are fairly similar. One is a GPS board and the other is packed full of sensors. I'm no good at programming so the sensor board gives me lots of things to work with. My previous setup was an uno connected to a breadboard with a ton of jumper wires. This packs everything into something that fits in the palm of your hand.
What about putting the ICSP pins as pads along one edge, three pads on one side and three pads on the other side. Then you can use a regular 2x3 header and shove it onto the edge, program, and remove. No soldering needed. Someone wrote a piece on that:
An ICSP header on the board edge is an excellent idea! I've done something similar by soldering a DB9 connector onto a board edge. The spacing between pins 1-5 and 6-9 feels like around 50 mil so once pushed onto the board edge and soldered into place was very rugged.