Xively (formerly known as Cosm and Pachube) is a cloud-based platform that provides remote access to devices like Arduino and many more. You can read condensed information about Xively by visiting https://en.wikipedia.org/wiki/Xively.
Using your web browser, visit http://xively.com/:
There is no link label to sign up in the web page, so type https://personal.xively.com/signup in your web browser's address bar and directly visit the Sign Up page.
After a successful sign up with Xively, you will get an e-mail with an activation link. Click on the activation link.
You will be redirected to the Welcome to Xively ...