I don't know about without the pc attached but here is one at donationcoder to use on pc. http://www.donationcoder.com/Software/Skrommel/#White
When i got this "flash of brilliance" my idea was to use my existing monitor and just tilt it back or modify an old shoebox or similar to set it on. Another option would be to hook up dual monitors. If you didnt want to hook up dual monitors you would need an old spare tower or an old laptop would work well also. Thanks pidbo i was going to use windows paint but thats handy.