So my girlfriend is a geek too (surprise! surprise!) and she has helped clients for years to setup computers, get rid of virus, trojans, malware, etc and most of the time clients just bring their desktops or laptops to her and she fix them and they pick them up good as new, but some times some clients don't have the time and really needs to get their PC's working quick, this is when VNC comes in. VNC for the non-geek audience is a software that enables people to control computers over the network, it's really the best way to fix a desktop computer remotely (servers are other story). What's the problem with VNC? well, the setup is tricky, specially when routers are on both ends and NAT needs to be setup properly before even trying to connect to the remote computer and most of clients aren't really even remotely geeky, they really have no idea what's going on with their PCs and they just need help. So, if you ever tried to tell a client how to setup VNC and their router over the phone, you will absolutely LOVE Fog Creek Copilot, I mean, you'll want to create a shrine to the developers that made this thing possible, it's that good.
Basically Copilot takes all the hassle out, put your name in a box or create an account, they'll bring you back a number, tell your client/friend/family to write the number down on copilot.com download and install the software. Once both have the software running Copilot will connect them and you'll have access to the computer. That's it!, simple, easy, fast, brilliant. No configuration, nothing. It has various pricing options but I found out that the day pass it's free on weekends and \$5 on any workday so we go ahead and tried that (I'm a cheap bastard, I know), and oh yeah, it works on OS X and Windows, which is even better.