I have a 10" Lilliput touchscreen on my desk which uses USB for power and video signal, not like some of the others that use HDMI and USB.
I find though that even though it's directly under my monitor, I am barely looking at it and it seems a waste of £30, although I could move it to my Pi I suppose but again seems like a waste.
It can play video so I could have YouTube on it incase I need to know something for a game but I use my 2nd pc for that, I could put other stuff on it but again I have a 2nd pc for that.
Don't get me wrong I like the idea behind it but I just think after getting this screen that it's a gimmick that actually once you have messed around with it, it loses it's appeal and becomes annoying.