Perhaps you could try asking Bill Prady on Twitter. He's usually pretty responsive with fan questions regarding the show. I've seen him answer a few questions about props on the set in the past.
I looked for electronic sketch pads, Older Wacom style drawing tablets, even universal remotes. I found lots of things that had similar features but nothing exact.
I even did a lookup of electronic company logos to see if I could match the logo on the bottom of the device. That would at least help identify who made sit.
The slider at the top is what is throwing me off. That's what is making me think it's like a Magna-Doodle or something, but maybe electronic.
No luck, but I looked hard for it for a good 2 hours for ya.
Anybody have a droid phone? There's an image recofnition app that works really well. Not just with logos but also with just an image of something. Maybe take a photo of your screen with the image zoomed in on the device and see if you can match it up with something.