Dropbox is one of the best file sync backup that ‘just works’. You just drop a file in a folder and it is synced across all your devices seamlessly without you lifting a finger.
If Steve Jobs created Dropbox he would have called it ‘Magical!’.
Dropbox iPhone app has been a huge success and I use it all the time to transfer files between my desktop and iPhone. Now, the app has been updated for complete iPad support.

In landscape mode, Dropbox offers the split pane view shared by Mail and other iPad apps. The toolbar offers options to jump to favorites, email a public link – copies the link to clipboard, account settings, mark as favorite and an option to choose an app to open a file.
In portrait mode, the app shows the document in full view without the sidepane.
Besides the iPad compatibility, Dropbox can also be set to open documents in Apps of your choice. Also, as a bonus the Dropbox also includes iPad app suggestions complete with icon, description and a purchase link.
You can also send documents like Word docs to iWork apps for editing.
Try Dropbox (free 2GB account).
You can read a lot on everything about Dropbox here.

