Here at DevCow, we're always interested in the next big thing. We're also always interested in the next free thing!
That being said, how would you like to have access to your home or work PC while not at that location? Or, how would you like access to your mother's computer...all the way across the country? There are existing solutions such as Remote Desktop and VNC, but these free solutions generally require known IP addresses or valid WINS lookups to find these machines. Firewalls also block these. There are others solutions such as the Citrix GoToMyPC program which work across firewalls and use a website to keep ever-changing IP addresses abstracted away from the user in the form of fancy graphics. The problem with GoToMyPC is that it isn't free.
LogMeIn.com uses the GotToMyPC model of web based access - you log into a website and see if your machine is available for remote control.
If your machine is online, a simple mouse click will connect you to the remote machine. According to LogMeIn.com's marketing material, you can even use this from a PocketPC device! It works as well as VNC to connect you to the remote desktop and is completely free for personal use. You are always offered the opportunity to upgrade to the Pro version, which offers the same kinds of extras that GoToMyPC offers like file transfer and remote printing.
Be sure to check out www.LogMeIn.com for your future tech support needs. I can't tell you how often I've had to talk friends and relatives through "complex" setting changes such as accessing e-mail and sharing printers. This tool, which lets me make the changes myself (required when it comes to registry changes!) is invaluable as it means I can shave valuable Xbox time out of a tech support call and I can show my "clients" what I'm doing rather than try to talk them through it. Now, if only I could find a free version of Adobe's Captivate software to record the session and generate a transcript out of my screen actions for future reference!