Seems like I was a little late to this party. What's the current state of Zaurus VGA?
The only card I can find that is still easy to buy is the Colorgraphic Voyager VGA card. It goes for around $150. But there's no way I can find to make it work in a Zaurus. Also the Margi card but it doesn't work either.
The Colorgraphic card has a bigger PCMCIA brother that does work on iPaqs, so maybe it's not that hard to adapt the driver?