I like what Tiny Circuits does. In the short, they give us the means to miniaturize our Arduino projects. If you need it, once your Arduino application is done, it is likely that you can shrink it to the side of a quarter.
I presented a stack of their products a year or so ago (1st link below). In another post (2nd link below), I walked you thru my build of an arcade MAME machine. So, when I learned that Tiny Circuits are selling a tiny arcade – a previous Kick-starter –, I could not resist. It is pretty cool, and now I can play arcade games on the go! Next step: learn how to add games to this tiny arcade.