I built a simple power supply using an adjustable LM1117, a multi turn potentiometer and a mini digital voltmeter from eBay. I used an old laptop transformer as power source (I don't like to work with high voltages :D )
This module is a LiPo charger for a 1 cell battery coupled with a charge pump (MCP 1253) providing 3.3V or 5V (by switching a jumper) with a max current of 120mA. The charger part is basically a small usb board based on the TP4056 IC.
My bachelor's degree thesis was about creating a GPS tracker, both hardware and software. The hardware part was based on the Atmega328 using a GPS module (SKM53), a SD card and a 74HC595 mixed with a couple of RGB Led's for notification.