Scott Hanselman has a 30% off voucher for MaxiVista an awesome 'virtual networked display adapter' that makes any computer that you can network to act as an extra monitor.  It's definitely worth downloading the trial at least.  Be warned though, you might find it so good that you may end up buying extra monitors (and here).  Once you've used multiple montors, it's hard to go back

When I first read about Scott using his Tablet PC as an extra monitor I thought it was something special with his tablet - turns out it was MaxiVista.  It can use any 'any type of network which supports the TCP/IP protocol (Ethernet, Wireless LAN. Firewire or USB network connection).'  The faster the connection, the better the performance.

I've been using it while I've been working on some hands-on-labs and demos.  I work with VPCs at full screen on my laptop and use MaxiVista to make my Tablet a second monitor that I use to display the word documents.  Christian Weyer uses the same trick when using Linux VPCs.