Maxivista is that software allows you to use your laptop or second PC as a second monitor via a network connection rather than using a second monitor. Laptops with video input ports are exceedingly rare and plugging a monitor out of one PC and into another is a hassle and only possible if your graphics card has two output ports. A vitrual graphics card is used to emulate the second output.

This software has a cult following in a few niches, notably among flight simulator enthusiasts.

Version 3 of the software is imminent (the price of version 2 has been cut by 30%), it will be fully compatible with Vista and has a range of enchancements to its feature set (nothing earth shattering mind).