If you have not cast a spell then I encourage you to push spells onto your twitter contacts with http://www.harrypottertweet.com

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This is a great use of twitter to launch something.  The experience design is simply magical.  The functionality offers a easy way to share and cast your spells. 

Cast the 4th and final spell!  http://www.harrypottertweet.com

ON: Harry Potter’s Tweet via @jpenabickley