A lot of great suggestions, thank you!

>The through-hole crystal is on the top side (where there is no copper) so =
this
>is not a problem, right?

Ordering SMD crystals didn't even cross my mind when I was getting the
capacitors and resistors. I guess just I thought of a crystal as being
a "through hole part", but really, there's probably an SMD equivalent
for every through hole part, isn't there..


>I would maybe make your pad rings a bit thicker

Are you talking about the pads for the crystal, or *all* of the pads
on the board? I just changed the crystal's pads (which were pretty
thin..) to be like most of the others. I'm not sure if I can make the
..1" spaced pads larger, though, because then there won't be much room
in between them.


>If using a simple pin header for power, I always make it 3 pins (one end
>pin no-connect) so that reversal does not result in a connection.

That's a really good idea!


>As I said before, I would arrange the pads so that one or more (ICD) board
>connectors could be used instead of soldering single wires to the board - =
they
>have a tendency to break when wiggled a couple of times.

There aren't going to be any wires soldered directly to the board. I'm
planning on using female break away headers for all of the I/O pins,
like these: http://www.sparkfun.com/products/115 . And then Male
headers for the ICSP connector, and I guess for the power pins, like
this: http://www.sparkfun.com/products/116 .


Somebody (or maybe a couple of people) mentioned that it would be a
good idea to have the option of powering the board from USB, and also
that having the USB voltage pin tied to a sense pin could be useful. I
tried adding two jumpers to accommodate this:

http://www.roboticsguy.com/images/misc/4550_SMD_pcb2.png

I highlighted the VDD traces. Is it alright to weave the VDD trace
between C3's (1206 package) pads? It looks like there's enough room,
both on the computer and on a paper printout, but I don't know if it's
generally an acceptable practice? Also, I made the VDD and GND traces
0.03" for much of the board, but will 0.02" be wide enough for the VDD
trace coming off the USB connector?


I tried following this image for the sense pin:
http://www.roboticsguy.com/images/misc/figure_17_11.png . The routing
looks a little odd, but I think it's the way the image shows it.


So, if this is works, I would be able to use jumper #1 to choose
whether or not I want to use an I/O pin on the PIC as a sense pin, and
#2 to power the board off of USB.
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