MailDrop automatically saves email attachments to Dropbox
Dropbox has to be one of the easiest ways to move files around. If you receive a lot of files in your email that you'd like to move into your Dropbox, check out MailDrop.
MailDrop is a Windows executable that will watch a specific folder in an email account, and download any attachments on messages it finds in that folder to the folder you specify in your DropBox account. It can connect to any IMAP mail account, and comes pre-configured to work with Gmail.
One use I can imagine is that you could set up a slide show to show images from a DropBox folder. Then, you could add images to the slide show remotely simply by emailing yourself files (or receiving files) and putting them in the corresponding folder.
MailDrop is likely only useful in specific scenarios. If you need it, you can probably already see how you'd use it.