I have always wanted to synchronize my files between computers seamlessly. I even thought of developing an application for it myself.. In fact, I was going to, at the first chance I get! However, I just found a pretty good freeware. (well only the 2 gb version is free; but hey, it is pretty good right?)
You can upload your files to your Dropbox either from the web interface, or by simply copying them to your Dropbox folder after installing the application. Any change you make on this folder is instantaneously mirrored on the web interface and other Dropbox installations on other computers.