The iPhone’s screen is well-proportioned for a pants pocket, but you wouldn’t want to use it all day as a dedicated computer monitor. Not if it was your main screen, anyway. But having a small screen off to the side can be surprisingly useful in a lot of situations. There’s a company called Mimo that specializes in these kinds of micro-monitors. Use them for chat, a color palette — anything that doesn’t need a whole lot of space yet tends to get in the way when it’s on top of the main window you’re looking at.