If you’re on a Mac, Cloud is a great free app.
To use it, you just drag a document onto the application icon in the menu bar and it gets uploaded to the internet. It then copies the link to the file so you can just paste it into an email or use it wherever.
To make it even more handy, it can automatically uploads screenshots you take and return a URL to the file to your clipboard. This is very handy when I’m writing an email or a form post where I want to include a screenshot.
It’s such a simple app that works extremely well and one worth checking out.