There's a pretty lengthy write-up on HuffPo.
Short version:
For one week each year, Rita Toews, 61, a soft-spoken mother of two and grandmother of one, sits at the center of the ebook universe.
Operating from a spare bedroom in her home in Winnipeg, Manitoba, Canada with her cat Lola by her side ("Every author needs a cat," she says), Ms. Toews is the creator and chief ringmaster of Read an Ebook Week, an annual international celebration of ebooks....
For the one week only, publishers and authors offer thousands of original ebooks for free and at deep discounts to encourage book lovers around the globe to give ebooks a try.
It apparently dates to 2004. The domain in the article, ebookweek.com, now redirects to Valor eBooks. Not sure of the relation there.