I use VMware Fusion at work to test my websites in different versions of IE by running multiple copies of Windows on my Macbook Air. At home, I use VMware Workstation to do the same thing. My desktop is powerful enough to do this without trouble, but my poor little Air at work huffs and puffs during testing. Is there a way for me to let my desktop actually run my virtual machines, and just access them at work on my Air?
Yes. The simplest solution would be to configure your virtual machine for Windows Remote Desktop Connection using RDP.
The VMware knowledge base has a guide for configuring VMware here, and you will also need to enable RDP access from within Windows. Note that some editions of Windows do not support RDP or are only able to access other computers.
If you find that you are not able to use RDP with your Windows virtual machine, there are many other screen-sharing and remote desktop software solutions. Wikipedia has a great list here.