This is an IO expander board for Synthia v2, 0.65mm pitch surface mount! 

Project is here https://github.com/simap/ucurrent

Based on David Jone's µCurrent (of EEVBlog fame), modified to be easy to make at home.

Measures current down to the nanoamp range!

This guy was a gift for my dad, inspired by some interesting wire sculptures he had when I was a kid, and would often tell me stories about my uncle's go-cart engineering efforts. A 1F capacitor would charge up until a blinking red led triggered launch, which would go several meters quite quickly!

Carefully balanced on 2 wheels.

I made a bunch of these as gifts. When you switch them on, they buzz around in circles. Recharged by solar.

Pager motor, on/off switch, a 20mah NiMH coin cell, 1x2cm solar cells snapped in half, and a germanium diode. 

This is all seeing bug tank! With a his beady eyes (CdS photo resistors), he can detect differential motion and move towards moving objects. Some springs and paperclips give him feelers so he doesn't get stuck on walls. One of my earlier PIC based projects, this used an original PIC16F84 with a 20Mhz crystal. Capacitor discharge timing was used to read the "eyes" without an ADC.