A sister site called The Armory offers weapons and ammunition.
They function just like legitimate online shopping sites and feature sellers' profiles detailing their trading history and customer feedback.
Sellers offer to vacuum-seal and post orders internationally, with a false return-to-sender address.
Yesterday, a NZ Customs spokeswoman - when asked if the site had affected attempts to import drugs - said there had generally been a significant increase in interceptions.
But the volume of drugs found on each occasion was often less than normal, meaning the total seized had not grown significantly, she said.
In a post on Silk Road's forum this week, an "official New Zealand thread" warned fellow Kiwis to keep a low profile.
"The more we boast about it, the easier our mail becomes to profile and target and we would be stupid to think that law enforcement doesn't browse these forums."
This year, a Dunedin university student and his associate used the site to arrange for 165 Ecstasy pills to be mailed from the Netherlands.
The drugs were intercepted by Customs and the Herald understands they were found to be pure MDMA - a rarity for Ecstasy in New Zealand.
The 18-year-old told police that he agreed to let the pills be sent to his address to help fund a 12-month exchange trip to Canada.
The extent of the Customs officer's use of Silk Road is unclear.
The Herald has been told that he claimed he used the site as research for his work. However, it is understood the Customs Service decided this explanation was unlikely.
Yesterday, the officer told the Herald he "wasn't using" Silk Road.
When asked why it was on his home computer, he said: "I knew about it, because I worked for Customs. But since I have name suppression, I'd like to make no comment".
The Herald accessed Silk Road and found a sidebar showing categories of listings.
There were more than 2000 listings for drugs such as cocaine and cannabis, with accompanying pictures, price-tags and product descriptions.
Forged drivers' licences and passports were among other offerings.
One US-based trader was selling custom-made John Key blotters - preprinted sheets of blotting paper that can be dipped in an LSD solution - "for all you Kiwi bastards".
Increased media attention has led to the site's community growing and, with that, a rise in scammers.
Last month, the Customs officer appeared in court on a total of 11 methamphetamine-related charges.
It is understood the man's alleged offending was uncovered during police inquiries into another crime.
The alleged offending was not directly related to the man's work.
Although the amounts of methamphetamine involved were small, a decision was made to press charges because of the nature of the man's employment.
HOW IT WORKS
* Silk Road is accessed through browsing software called Tor - The Onion Router - which bounces users' connections off multiple servers worldwide. This is said to make identity untraceable.
* Tor was developed by the United States Navy, and has been hailed by campaigners as a way to retain free speech and avoid censorship.
* Two US senators have urged the United States Attorney-General to crack down on Silk Road and the digital currency that enables purchases on it, Bitcoins.
* Goods on Silk Road can only be bought using Bitcoin, an independent online currency.
* The peer-to-peer currency, which works via a piece of open-source software, aids anonymity on Silk Road because it is not linked to any institution.
* Bitcoin developer Jeff Garzik has previously said that because the currency log is public, it's possible that buyers could be tracked. "Attempting major illicit transactions with Bitcoin, given existing statistical analysis techniques deployed in the field by law enforcement, is pretty damned dumb," he told Gawker.com.
