To kick off the Adafruit HAT party, we have this Perma-Proto inspired plug in daughter board. It has a grid of 0.1" prototyping soldering holes for attaching chips, resistors, LED, potentiometers and more. The holes are connected underneath with traces to mimic the solderless breadboards with which you're familiar. There's also long power strips for +3V, +5V and Ground connections to the Pi. Near the top we break out nearly every pin you could want to connect to the Pi (#26 didn't quite make the cut).