My latest flea market find is a Magellan eXplorist XL GPS receiver. It was claimed to be broken and sold for €3. Inside it had an SD card containing detailed maps for the whole country. I took it home, changed the batteries and looked inside. Turned out one of its battery terminals had been installed backwards and was not touching the battery. Amazingly, this was the only fault it had, and after fixing it I now have a working GPS receiver!
I've tested the receiver on walks and bike trips. It works perfectly and is very accurate. The maps are detailed and quite up-to-date (from 2007). I can type in a street address and it will calculate a route for me. It even knows many shops, restaurants and public services.
The device has a peculiar connector on the backside. Markings on the PCB reveal that it's a custom USB connector. This was probably the only way they could make a USB connector water-proof. I don't need water-proofness but USB would be fun, so I cut a hole on the side and installed a standard USB-A connector instead.
This hack actually works and the eXplorist is recognized (as a modem for some reason). Turned out the device can even communicate with Linux using NMEA, so I can now install gpsd and do all sorts of fun location aware stuff on my laptop!
Later I've downloaded more maps to the device from OpenStreetMap. They're awesome! Some Python scripts need to be used for map conversion (pymagellan).
As an added bonus, Magellan has chosen the highly-acclaimed Comic Sans MS as the font for all menus.