CrossRoads:
You should add a diode across the 10K resistor, Anode to power and Cathode to Reset, will keep the chip from attempting to go into High Voltage programming mode
Will any diode do for this job, or is it important to have a specific breakdown voltage? An ESD diode is mentioned, but I gather this is a description of its role rather than a type. I'm wondering about a 5.1V Zener diode wired in the direction you describe. Does that sound sensible? Here's a link to a possible part for the job...
CrossRoads:
I've not found the cap to ground to be needed. Likely the DTR cap makes it stable enough.
Initially I couldn't figure out which cap you found wasn't needed, but looking at the datasheet http://www.atmel.com/images/doc2521.pdf in more detail I can see figure 3.1 with a recommended circuit including the suggested diode and an extra cap. I think you're saying leave out the extra cap from their circuit as it's not needed.
CrossRoads:
Also put a 100nF cap from Aref to Gnd, will be needed for stability if one is doing any analog measurements.
I'll add this one.
I find I'm adding a lot of extras, now. Are there any bits I can sensibly remove from the circuit as it stands for a general purpose Arduino compatible? Especially wondering about the 10microFarad electrostatic from VCC->GND. I'm a bit vague about the circumstances under which it would do me any good, given there are already 100nF caps placed between VCC-GND and AVCC-AGND.