It's often seemed to me that there is something of a gap for an 'open avionics' suite to be developed for the homebuilt market. Though I'll admit I haven't looked to see what's available already. I do a fair amount of home electronics - enough to realise I probably wouldn't trust my life to anything I designed - but when I look at the prices of relatively simple things like tachometers and engine temperature gauges I can't help thinking that a little PIC and graphical display could do the same job for a fraction of the cost.