I've just published a Google Chrome Extension that makes Newgrounds a little safer to visit. Not by blocking any content, but by filtering some thumbnails for M and A rated content. It's version 0.95, which means that it's not tested a lot yet, but it's otherwise finished enough. Once it hits v1, I'll make a proper post about it, but for now, this should do quite nicely: http://www.brianorchosky.com/chrome/ngfilter.html

And for a direct link to the extension: https://chrome.google.com/webstore/detail/newgrounds-filter/phchlhgfejopgcopjdndleaohemaddim/details?hl=en&gl=US