There's an old business saying: If you want to make money in a gold rush, don't prospect, sell shovels. This is the same sort of idea that happened with Twitter and URL shorteners.

URL shortening services are the shovels of the Twitter gold rush, except nobody's making any money selling them.

Because Twitter limits its posts to 140 characters, URL shorteners such as bit.ly and TinyURL are a necessary tool for link sharing and re-tweeting, activities which are now major methods of news circulation. Tr.im was another link shortening service, maintained by The Nambu Network, which received nearly one million unique visits a month.

Unfortunately, though their "shovels" were being used, there was no way for Nambu to make any money, and the site has begun its shutdown process.

On its home page, a message reads:

"Statistics can no longer be considered reliable, or reliably available going forward. However, all tr.im links will continue to redirect, and will do so until at least December 31, 2009. Your tweets with tr.im URLs in them will not be affected. We regret that it came to this, but all of our efforts to avoid it failed. No business we approached wanted to purchase tr.im for even a minor amount."

Since Bit.ly has become the default URL shortener on Twitter, Tr.im simply cannot afford to hang around.

"There is no way for us to monetize URL shortening -- users won't pay for it -- and we just can't justify further development since Twitter has all but annointed bit.ly the market winner," the site's farewell message says. "There is simply no point for us to continue operating tr.im, and pay for its upkeep."

Bit.ly has reportedly offered to host the millions of Tr.im URLs so they do not disappear on January first when the service officially closes down, but there is no word on whether this will take place yet.