Skype now has 299 million connected users. Bing sends 1 billion mobile notifications a month. SkyDrive has 250 million accounts. Outlook.com is also able to gain 1 million users in its first 24 hours of availability and Office 365 now has nearly 50 million Office web app users.
These stats were released at Build 2013. Click here if you are interested in reading about Azure-powered online services.