By Doug Gross
(CNN) -- Authorities say Silk Road, the shadowy "deep Web" site shut down by the FBI this week, was the Internet's biggest destination for drugs and other illegal goods.
It had nearly 1 million registered users, the bureau says, and was used for roughly $1.3 billion in transactions over the past two or so years.
But shuttering Silk Road and arresting its owner won't be the end of the shadowy black market on the Web, where drugs are far from the only products that can be bought illegally.
The so-called "deep Web" consists of sites only accessible using tools like Tor, which includes a browser designed to hide the user's identity by routing their activity through a series of remote connections. Many sites use intentionally cryptic web addresses -- Silk Road's last was "silkroadfb5piz3r.onion" -- that spread stealthily via word of mouth.
Here is a look at just some of the illegal goods that have been documented as offered for sale on these underground sites. (We're not linking to them, sorry.)
Maybe it should be no big surprise, but hours after Silk Road was shut down, Web users were flocking to online forums with one question: "Where can I buy my drugs now?"
The answer? Take your pick.
Sites with names like Sheep Marketplace, Black Market Reloaded and Deep Bay were just some of the ones being mentioned as possibilities.
Another, called Atlantis, had emerged earlier this year as a Silk Road competitor with an aggressive social-media campaign. In June, someone claiming to be the site's owner even conducted an AMA ("Ask Me Anything") session on Reddit.
"We want to bring attention to the site and bring our vendors more buyers," that person said during the session. "Law enforcement is going to be aware of us (and probably already is) regardless of the way we choose to put our product out there."
Two weeks ago, Atlantis announced it was shutting down due to "security reasons outside of our control."
Illegal guns can be found on similar sites, as can legal weapons by people who may not pass a background check or otherwise be allowed to buy them.
Last year, Gizmodo reporter Sam Biddle spent some time on The Armory, an offshoot of Silk Road devoted to weaponry. As part of his reporting, he posed as someone arming a paramilitary group bent on "taking on a 3rd world government organization." The helpful responses poured in.
"I can provide: tec9, scorpion, ak47 and one single vietnam war 'thumper', but its ammo costs," read one, the final reference being to a grenade launcher.
"Absolutely, we can accommodate your request, but we need more parameters such as your exact arms needs and destination country," read another. "We only deal with small arms and equipment, but if you need artillery, MANPADS (Man-portable air-defense systems), ordinance, APCs, Helos we do have resources and can make certain introductions for a fee."
About a month after the Gizmodo piece ran, Silk Road's owner announced it was shutting down The Armory, citing high prices and lack of interest.
The International Fund for Animal Welfare calls the illegal sale of wild animals online "one of the major wildlife conservation challenges of our generation."
"The rise of the Internet has revolutionized the way we exchange ideas, information and merchandise. ..." reads a report from the group. "However, as a result, the Internet is also facilitating the illegal trade in wildlife, which is having a devastating effect on animals, ecosystems and the communities that rely on them worldwide."
The report, in which the group tracked activity on 183 websites, documented the sale of elephant ivory, birds of prey, tigers, large snakes and other rare or endangered creatures.
The relative anonymity the Web provides, combined with a patchwork of laws from state to state and country to country, make policing animal trafficking a tough job, the group said.
Along with drugs, firearms and solicitations of hackers, Silk Road also had forged documents for sale, the FBI said.
In July, the FBI says it intercepted nine false IDs bound for Ross William Ulbricht, who they say is "Dread Pirate Roberts," the man behind the site. "Roberts" had been soliciting fake identification documents on Silk Road to use in buying more server space for the site.
It shouldn't have been hard.
A simple Google search for fake passports renders websites like FalsePassports.cc and IdentificationConsulting.com.
Need a "novelty" driver's license? Several sites offer those, and you can get a diploma and Social Security card while you're at it.
"For your own personal use and amusement," notes Global Intelligence ID Cards Solutions.