First task of the day here at Indigo was to pick the iPad 2 Air winner from among those who left a review before the Solstice. 49 review in all, thank you very much! We went to Random.org, a random number generation site, keyed in the variable and submitted for the result. Random.org uses several radio receivers around the world to pluck randomness from the atmosphere, somehow converting atmospheric noise to integers. I didn't realize how complicated this was until I lost a few hours looking through their FAQs. Interesting, indeed.
The result returned was "21." Ironically and randomly, the date of the Solstice, which has been the organizing principle behind this event.
I have just e-mailed 'Lisa' with the good news...
Thank you all again for your feedback and your kind words.