Wordorigins.org has a list of around 400 word and phrase origins. The words and phrases are selected because their origins are inherently interesting or because some bit of folklore, sometimes true and sometimes false, is associated with the origin. Many of the words have been added as a result of questions or suggestions from readers of the site.
Here's the entry for Cyber Monday (which happens to be today!)
And the Monday after Thanksgiving has been christened Cyber Monday. This day is alleged to be the busiest online shopping day of the year—with people using their internet connections at work to shop. The day, however, is not the busiest online shopping day of the year. In fact, it is nowhere near the busiest online shopping day.
Cyber Monday was coined on 19 November 2005 when Shop.org, an association of online retailers, made the claim to the New York Times that it was expecting a “substantial sales increase” on that day: "Hence the catchy Cyber Monday, so called because millions of productive Americans, fresh off a weekend at the mall, are expected to return to work and their high-speed Internet connections on Nov. 28 and spend the day buying what they liked in all those stores".
That begs the question: What is the busiest online shopping day?