Depending on your planned enclosure, you may want to consider placing the Servo, Interrupt, PPM and Serial headers on the bottom side of the board. For instance, when the headers are on the bottom of the board and the board is mounted with standoffs to the side of an enclosure, the headers are easily accessible via a hole in the enclosure. This will allow you to plug servos and other cables directly onto the headers from the exterior of the enclosure.

Controller with minimum req'd components to produce serial data

The minimum components required for serial data to appear on the RS232 header are:

1. Max231 (U5)
2. AtMeg163 (U1)
3. 8Mhz Crystal (X1)
4. 22pF Capactors marked as 220(C2, C3)
5. LM7805 Voltage Regulator (U6)
6. De-ripple .1uF Capacitor (C7)
7. Max231 Pump Capacitors (C5, C6)
8. .1inch 5POS Headers (H, RS232, I0, I1, P)

[...]

$GPADC,01C0,01B5,0204,01DD,0255,0231,0213,01DB
$GPADC,01C9,01BC,01FE,01D5,0257,022F,0211,01D6
$GPADC,01CB,01BE,0201,01D9,0250,0230,0215,01D9
$GPADC,01C4,01BF,0201,01D9,0254,0234,0211,01D5
$GPADC,01C6,01BF,0204,01DC,0257,022F,0211,01D5
$GPADC,01C8,01C3,0204,01D7,0251,0233,020E,01D4

[...]

The P input is for a PPM signal. This input utilizes the PN2222A transistor.

The standard servo headers are number 0 through 9 and one high-speed servo header is labled H. External power is required to drive the servos. All 11 servos (10 std & 1 high-speed) share the same power bus.