Even some of the darker areas of the Internet offer chances to crowdsource in extraordinary ways. 4Chan.org--NSFW and often called the armpit of the Internet--has shown its crowdsourcing power numerous times, most often behind the leadership of hacking group Anonymous and their powerful denial of service attacks. Like a swarm of bees, the users of 4chan have collectively worked with Anonymous to use power in numbers to shut down Playstation's network or the Egyptian government's websites. This power, especially with a youthful audience, can be helpful in collecting data as well. Ask a question your own teenager might be fearful of answering for you, and 4chan may provide information.

Even moreso than on other sites mentioned here, be careful how and what you post. 4chan topics and discussions can turn ugly or take on a mind of their own. Keep your posts and see what you get back. You might be surprised to find the good information that comes from the site and its faithful users.

This cautionary note bears repeating: As I previously stated in , the questions you post in any online forum become public and can be found by anyone, including your suspects, clients and peers. Make sure you are only posting need-to-know information, with limited (if any) details about your investigation or who you are. Posting on a tattoo message board looking for a specific gang tattoo and saying you're a police officer might get zero responses. Instead, consider adding : Say you saw "the gnarliest MS13 tattoo" and are looking for a tattoo mentor in East Los Angeles. You might just get the answer you are looking for.

Next time your leads dry up and you can't find any answers, try crowdsourcing online. The amount of data I have received from posting on Craigslist's Missed Connections and Rants & Raves alone has been unmatched by any database site I pay for.

Best of all: It's free and anonymous.