I love dropbox. I have been using it for years. It is a program that you install on any computer/operating system you have and it keeps them all in sync. It puts a folder on your computer and anything you put into the folder is auto synced to an online server and then synced to any computer with your dropbox account.
It is handy on the iPad because you have all of your files with you where you go. If you don't have 3G on your iPad (I don't), then you can save your favorite files.
The best part is that it makes syncing things like notes really easy. I can take notes on my iPad, iPhone, or computer and keep them all in sync.
I certainly do not work for Dropbox, but I am a big fan because they have made my life much easier. Just my 2 cents.