A couple of days ago, I found a little nice potion of software. It’s called pspdisp. This software extends the windows desktop on your Sony PlayStationPortable.
The software contains of two parts. You have to install one part on the PlayStationPortable, the second part, you have to install on your Windows PC.
Pspdisp allows you to connect the PlayStationPortable with your Windows PC via USB or via WLAN. I only tried it via USB. In the display properties dialog, you can setup your new screen.
On my analog desktop,I still got two displays, but with my PlayStationPortable, I got a thrid one.
Ok, the resolution is not very large, but for small applications it is enough.
On your PlayStationPortable, you need a costum firmware.