I want to have remote desktop on the internet so when im away from my server at work I can remote desktop it :)
I currently use LOGMEIN (www.logmein.co.uk) but I've also used GOTOMYPC (www.gotomypc.com) in the past; both worked well but the former was a bit cheaper! I think there are several others but these are two I've used and can recommend.
You can use the remote desktop utilities built in to most "professional class" operating systems and access it using any other computers compliant remote desktop program and your IP address.
This, however is a tremendous pain in the ass if you're behind a router. I personally use the free version of logmein.com. It installs a small program on the computer and then you just need a web browser with Jave. It sorts out the network settings on it's own, and gives you a list of all the computers you have set up when you log into your account. I even use it to access desktops from my cell phone sometimes.