I use a galaxy note 10.1. It's pressure sensitive and comes with a wacom S-pen stylus. It's good for starting these things on site and taking notes for later. Also snap a couple of photos. I will do as much as I can this way because it is so convenient, but glare on screen and colour calibration is a constant issue to deal with.
Digital Plein air-ists have custom made setups for their laptops. Check out Shaddy Safadi's setup.
Thanks a lot for your answer ! This is something I've been wondering about for a while. I agree that this is a really interesting concept and sometimes I'm thinking "damn, I'd like so much to paint this with these awesome colours right here right now... and my damn cell phone doesn't take photo with good enough colours (essentially for sunsets so usually I photoshop my photos or try to paint the sunset from memory...). Why can't I take my watercolours or my photoshop everywhere ?"
Now I see how an artist can use this kind of tablets thinking about it, my mother should lend me her galaxy tab... maybe I'll be able to digitally sketch with it !
No problem. The best way to learn and improve is to paint/draw from life, so it is worth the effort. I must try and do it more. I actually think traditional painters have it easier in this respect. They don't need electricity!
Yeah have a play with tablets, the galaxy tab won't have pressure sensitivity but you can still have fun within the restrictions.