USB powered and connected laptop monitor for $100
Not sure how many people will find this useful for photo editing as it has a horrible color gamut (looks like 75% sRGB or something, though my MacBook display isn't much better), and a horribly narrow viewing angle, in addition to being a TN display that probably only displays 6 bits per channel, but anyway:
Though it would ordinarily be just a horrible monitor, this thing is USB connected using a DisplayLink chipset AND USB powered as well. So no video port used, no power adapter, and unless you lack a full power USB port it only needs one USB port. It's also light as air and it's a second display for $100 that fits in my backpack. Actually I think the price is going up to $140 on apr 1 or something.
Also note that because of the USB connected DisplayLink video adapter chipset, the CPU has to do most of the blitting that a regular GPU based chipset would ordinarily do, so it will just peg the CPU like crazy if you try to display video or play FPS games on it. Basically it's no good for graphics or video, but it's good enough for displaying web pages, documentation, or whatever.
It has only one microusb port for connection to the computer. No brightness or contrast controls or controls of any kind.
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from Ink and water
|Kylmä joki kopio by Kaappo|
from Shutter speed 1/25 or slower
|WR_2.8_13 copy copy by photoprof|