Drop Box synchronizes files between computers across the room or across the internet. The service is free if you have 2GB of data or less. For $10 a month you get 50GB of data storage. I’ve used DropBox for several months now, and have to say that it works great. It makes it much easier for me to quickly share documents between my Laptop (mac), my Work Computer (windows), and my Home Computer (mac).
Not only does it facilitate file sharing, but it also serves as an excellent backup system. While more expensive than Mozy’s $5 a month backup service, you do get a lot of extra functionality that Mozy does not give you. DropBox works great on Mac, Windows and Linux computers, which means that it can be used on virtually any computer you own or can currently buy, including one of those cute little Net Books.
Another feature that some might find useful, is the ability to share sub folders with other people for collaboration purposes. As files are modified, previous version are kept so that if necessary you can revert back to a previous version of the document. Files that are accidentally deleted can also be recovered, unless you manually purge deleted files.
I highly recommend DropBox for people who use multiple computers and need to share files between them. Good luck!