Dropbox to ferry files around using the public folder, don't miss this time-saving Services add-on.

Once installed, right-click on any file on your Mac, select the 'Services' menu, then choose either 'Move' or 'Copy to Dropbox.' That's it. Your file is moved (or copied), and the public link to the file is copied to your clipboard, ready to send.

Many more useful services are available at Mac OSX Automation.