Time is running out for those wishing to enter one of the world's best-known ad prizes, the North American Effies. Agencies now have just three days to get their campaign case studies in by the last-chance deadline, which this year falls on February 4th.

The awards, which have been going in some form since 1968, introduced two new categories to the roster for 2011: Shopper Marketing and Single Impact Engagement, described by the organisers as "marketing ideas that had the ability to burn intensely for a finite period" for an "immediate and measurable impact". These new prizes join a long list of established categories, ranging across most product sectors, target demographics and campaign budgets.

Marketers in need of some last-minute inspiration for their entries could do worse than browsing the complete list of 2010 North American Effie winning case studies available to warc.com subscribers. These cases include last year's Grand Effie winner, 'I'm In', an integrated campaign led by Leo Burnett and Starcom USA which helped to turn around Detroit's recession-hit public schools system.

Alternatively, for a full list of upcoming global awards deadlines, calls for entry and other dates, please check our Global Awards Calendar.