Pretty nice. I have comments;
1) The dual/bicolor LED setup looks prone to lighting both LEDs if the output pin is tri-stated. Aren't most bipolar LEDs will be common anode/cathode (three leads) or inverse parallel (two leads), requiring two pins to drive both colors.
2) The pinout you show for PN2222A does not match my Fairchild datasheet.
3) Aren't MOSFETs generally usable without a gate resistor? It may still be a good idea, but....
4) Your speaker connection looks a lot more complicated than anything I've ever used (normally something more like the circuit you show for a buzzer.) It bothers me a bit to see the connection to +5 pointing downward...
5) The speaker, buzzer, and amp circuits are all designed to be connected to digital square-wave outputs (tone library, etc), right? Not fancier schemes from the PWM outputs.
6) the 5x 1.5V battery circuit will be questionable if used with rechargeable batteries (1.2V each) or cells near their end-of-life.
7) The "TTL/CMOS" converters are rather obsolete and misleading. Almost all CMOS ICs that people will encounter today are 5V and will connect directly to "TTL".
What kind of Mic is used in the microphone circuit? If it was a common electret mic, don't you need a DC blocking cap between the mic and transistor?
9) The Servo connection shows one of two common servo wiring schemes.
10) The 7-segment display circuit assumes common-anode displays, but it doesn't say that.
I think that's all for now...