I would like to make an NGT30.  A few features I plan to add are follows:

• Faster serial interface
• Mostly SMD components
• on-board arduino reset button for mega and similar boards
• More commands
• A way to add mods to firmware/GPU if I use an FPGA

I may even remove the Parallax Propeller and replace it with an FPGA.  FPGA, not CPLD, because I would do some really killer stuff with it that may require an FPGA.

I would like to make it backwards-compatible with my NGT20, so the serial interface must consider this.  I am mostly thinking about SPI, maybe I2C.  I would probably have some command to enable the new serial interface.  I would probably forget backwards compatibility if I used an FPGA however.  That would solve every problem :P

I want to use SMD so that the board size is smaller, the BOM is less, and the parts cost less for the same quality.   This way the overall production price is reduced.

I want to add the arduino reset button simply because it is really hard to reset my arduino mega with so many shields.

Finally, I would like any suggestions.  If you're considering getting some kind of video shield or nice display output (or already have one), what would make things better?