Sometimes I'm on the road but still doing some heavy duty work and having a second monitor helps. Carrying a second monitor is out of the question. I have thought about bringing extra cables and using my hotel room TV. I have even thought about buying an external pico projector. However, since I have an iPad, I thought I might as well use that as a second display.
I researched the following options:
ultraVNC / Mocha VNC Lite - as described here
Air Display - Shelve it for now as it costs $9.99
iDisplay - I stayed away from this one due to some bad reviews.
MaxiVista - I stayed away from this one due to some bad reviews.
OnLive Desktop also popped up in my searches, but from what I can tell it gives you a whole Windows environment and not simply a display
I ended up using DisplayLink as it seems like it was built specifically for my purpose.
The installation was smooth, but it appeared to have screwed up some Bluetooth driver as my Bluetooth mouse no longer worked. It could be coincidence, but I had to reinstall the driver after installing DisplayLink and everything worked again.
I wish there were one that would connect over Bluetooth instead of over wifi, but I will take it for now.
Now to buy a cover / stand.
[Update - 2012-06-07]
Got BSOD coming from dlkmd.sys twice yesterday before deciding to uninstall. I haven't even used it for a few days. In both cases, it may have happened when my machine locked itself for being idle.