The call for definitions produced a tremendous showing from a lot of very smart readers, both in comments and emails. At this rate I'll have you all writing the entire book for me in true Stone Soup/Open Source fashion. Thanks in advance!
Quite of few of you were able (easily, by the looks of it) to improve upon my own efforts at defining The Long Tail. For what it's worth, my definition D--"The Long Tail is about the economics of abundance—what happens when the bottlenecks that stand between supply and demand in our culture start to disappear and everything becomes available to everyone"--got the most votes, although I wouldn't call it a mandate by any means.
I'm not quite ready to pick a winner yet (or more likely remix good bits into an all-star mashup) but I can at least offer a finalist list. Ideally, the three key elements of the Long Tail that a good definition should explain are: 1) the shift from hits to niches; 2) the economics of abundance (infinite shelf-space effect); 3) the aggregation of many small markets to make a big one.
These are the ones the are closest so far (several were articulated by more than one person; in those cases I've usually picked the shortest one; I've also tweaked a word or two):
- "The Long Tail is the realization that the sum of many small markets is worth as much, if not more, than a few large markets." --Jason Foster
- “The Long Tail is what you get when the obscure becomes ubiquitous.”-- Eric Akawie
- “The Long Tail is the 80% of stuff that didn't used to be worth selling.”--Greg
- "The Long Tail is the story of how products that were once considered fringe, underground or independent now collectively make up a market that rivals the bestsellers and blockbusters." --Bob Baker
- “Trickle-up economics!”—Joshua Wood
- “The end of the 80/20 Rule!”—Eric Etheridge
- “Everything, all the time!”—Jim Treacher (channeling Don Henley)