If you regularly cruise potentially off-limits sites at work, get the safe sites sorted out with No-NSFW. “NSFW” (or Not-Safe-For-Work) is a universally-adopted acronym for sites that you wouldn’t want your boss to know you visit during working hours.
No-NSFW is a FireFox add-on that identifies offensive sites. All the information is user-submitted, so at this point, the majority (69%), of already submitted links remain unrated. Beyond that, 30% of sites are safe, and just 1% (5,500 links) are deemed unsuitable to read during working hours. The add-on automatically opens a small pop-up rating for every external link that a user hovers over.
Nonsfw.com In Their Own Words
“No-NSFW is a people powered Not-Safe-For-Work content warning system.”
Why Nonsfw.com It Might Be A Killer
As people become more comfortable (and/or obsessed) with blogs and online content, it becomes important to set some sort of monitoring device for this content in the work environment. No-NSFW is a user-voted standard.
Some Questions About Nonsfw.com
How can individuals gauge what may be acceptable at one company and not at another? Pornography, of course, is a universal no-no, but other sites are much less clear. For example, a site combining media and celebrity culture is not so easy to define. 
