When extended to business, this ratio measures the cost of overhead or transaction costs for each dollar's worth of goods or services delivered. That is, while the item you purchase may be itself worth only so much, the final cost to you factors in advertising, transportation, management, profit and so on. This is why a one dollar sneaker costs you over a hundred.
While these very hard economic scenarios are very interesting in and of themselves, they do not immediately provide insight to maintaining online communities, which are actually merely volunteer organizations. However, if you consider the resources we have to manage here are people's time and interest, then it becomes more apparent. The most pressing example here is the number of PeerReviewers necessary to maintain a wiki--not against vandals, attackers, and klutzes--but against the disorder inevitably created when authors mob the site. Other tests of PeerReview include rating systems as they demand enough reviewers to meaningfully sift the chaff from the wheat. This, of course, does not mean that you can slack off from your PeerReview responsibilities--completely the opposite, in fact, as without your efforts, the community cannot grow.
As online communities, we might also determine how much bandwidth to acquire using the TeethToTailRatio. As any system administrator of a timesharing system knows, you can easily get away with purchasing a small fraction of the bandwidth necessary to have every potential user online at once. This is because users do not all use the system all at the same time.
Like all economic tradeoffs, they are fragile and capable of being busted. On Christmas, the telephone system implodes as most users indeed use the system all at the same time. The other option is to overbudget like modern suburbian shopping malls. They must have enough parking spaces for the Christmas rush. This abuse of resources leads to decay, however, as symptomized by CarCulture. Perhaps the online equivalent is the extra bandwidth site proprietors must purchase as a cushion against the SlashdotEffect; the result is an overinvestment in bandwidth instead of the investment in a better web protocol.