Adafruit do display modules you can read in daylight but direct sunlight might be to much.
They also do eInk displays that will read in direct sunlight (think ebook reader) but in darkness you will need to light the display to see it.
I have also seen companies (cannot find links now) that will supply/modify TFT panels to add a special transflective film between the LCD & backlight to make them readable in sunlight but not sure if you can get them in small Arduino drivable displays.