The 3rd Friday in April 2011 wasn't the 13th, but it probably felt that way for a number of online scammers.

Gambling

Operators of several gambling sites,  Pokerstars.com, Fulltiltpoker.com and Absolutepoker.com and their online payment processors were charged with money laundering and fraud. Site domains and billions of dollars were siezed. It has long been known that these sites are dodgy, Joseph Menn laid much of it out in his book Fatal System Error (2010), with allegations of organized crime involvement, rigged gaming, and so on, and Journalist Brian Krebs made mention of money-laundering-by-gambling in 2007.

What Krebs alleges had been confirmed to CAUCE by federal investigators in private discussions years prior to that. The scam is easy, the perpetrators take a large amount of cash (usually stolen), and lose it to associates in online gambling games. Online thieves aren't the only people who avail themselves of this, terrorists use the scheme too, which may go some ways to explain the United States' stance on online gambling.

Online fora and Twitter went wild soon after these closures, with many noting that money they had in accounts on these sites was frozen and seemingly lost. The (big) house always wins.

Acai Berry "News" Reports

You've probably seen the spam, where you click through a link, and end up with what looks like a news reporter, extolling the virtues of Acai berry as a cure-all.The FTC put an end to some of that, charging 5 different companies behind this ubiquitous scam. Some of the domains the spammer/scammers used were

breakingNewsAt6.com
channel2local.com
channel6reports.com
channel9healthbeat.com
bhannel9NewsReports.com
consumernewspick.com
consumertipsdaily6.com
healthnews10.com
news4daily.com
theconsumerweeklydigest.com
usahealthnewstoday.com
usahealthreportstoday.com

(While CAUCE thinks Acai Bery is a yummy drink, your local supermarket is a cheaper alternative to buying the stuff online from spammers)

Good riddance to bad garbage. We should take a moment to note that just because a site has the word 'consumer' in its domain name doesn't mean it has your best interests at mind. Caveat emptor, always, and especially online.