I just LOVE MaxiVista!
I found MaxiVista through Scott Hanselman's post on multi-monitor productivity. I installed it a few days ago and I LOVE it already. It's not just that I can use my old laptop as a second monitor for my new one. It's not only working with Visual Studio 2010 spread across two screens. Or having TweetDeck on the second screen (oops, laptop) with VS 2008 on the primary screen (ooooops Laptop, laptop, laptop!). Multi-monitor debugging, side by side comparison of requirement documents and big excel sheets. Running VS on the primary, Team Explorer on the secondary screen.
It is that MaxiVista allows you to switch between the second laptop's desktop and the primary's extended desktop just by pressing a key and still use the primary's keyboard and mouse. The clipboard also works across both laptops. If this isn't the easiest way to remotely control another PC, I don't know what is!
If only I could do the same with Remote Desktop connections, I would be really happy!