first, the url.
www.logmein.com
I stumbled accross this website last week, and since then i've been using it every day. Basically what it does is lets you access your PC from anywhere in the world via your web browser - in a similar manner to remote desktop. You install a small piece of software on your computer at home, and then leave it switched on and connected to the internet. You can lock your pc/leave it on screensaver/whatever as long as it is switched on and has an account logged in.
Then you goto logmein.com, and login, select your PC from a list and a few seconds later you are at your desktop. It works via an activeX plugin (best way) or via a java applet, or if your browser is really locked down/obscure than a basic screenshot based html interface. From here you can do (almost) anything you would normally do on your home pc - browse the net, work, play simple games etc etc.
This is most useful for people stuck in an office IT job all day, where most PCs are locked down to some point - normally you can't ftp out of your company network, let along telnet or remote desktop. Logmein get's around that as it is all done through your browser on standard ports. It also gets around any monitoring that your IT team has - ie you can browse the net unrestricted and without fear of someone comign along and saying you have been posting on hexus all day instead of working - as far as they know you are simply logged on to logmein.com, that's it.
Performance wise it's similar to remote desktop when you use it over the internet, and it's affected by which plugin you use (activeX is fastest, java is predictable a bit poo, and html screenshots..well you need to be desperate )and your internet conncetion - but it is more than useable. My main use for it is to be able to telnet and ftp to my website/uni servers while I am at work, as I don't have access to those resources normally. It could also be great if you were away for whatever reason and need to get on your home pc to check a document or photo etc, simple to use
Best thing is that it's free..you get a free trial of the pro version when y ou sign up, but the only different really is that in the pro version you can transfer files to and from your PC - with the free version you can't. but it's simple enough to upload stuff from your main pc to an ftp/YSI/rapidshare or something.
I have probably explained it badly and have defo rambled on, but it's worth a look