Not as old, but I miss using my Essentials PH-1. It had stock android instead of a carrier or maker version of android and some really cool features.

The add-on possibilities looked good, since it had two power pads on the back with a magnet, and wireless USB interface.

You could mag click on adapters to add hardware.

I had the 360 video camera add on, and the company folded before I had a chance to purchase the audio DAC headphone add on.