While the association between so-called "friendly bacteria", and redued allergy, has been noted before, no-one is sure why they should have such an effect.

BBC: Live bacteria 'could prevent allergy'

As of today, the add-on seems to flag 333 sites as SOPA friendly, from industry groups like the Motion Picture Association of America to the Business Software Alliance, to companies like Apple.com to Nintendo.com, to Newscorp-owned sites like Fox.com and Sky.com.

FORBES: Chrome Add-on Tells You When You're Browsing A Site That Supports SOPA

This all follows the Football Association having called off the Netherlands versus England friendly at Wembley, among others.

FORBES: Will London Street Violence Ding or Enhance the EPL Brand?