What sets Cortana apart from other digital assistants like Siri or Google Now is extensibility by 3rd party developers.
Windows Phone developer Nivesh Singh took advantage of this in his Quotes app to allow users to ask Cortana to deliver an inspirational quote on demand.
The voice commands also work in Windows Phone 8.0, and the app can deliver Quote of the day, Love quotes, Inspirational quotes, birthday quotes and more.
Developers who want to do the same for their apps can read more at Channel 9 here.
The free app can be found in the Windows Phone Store here.