It's National Grammar Day in the USA on March 4th, and this webpage has lots more information about it is being celebrated. Among my favourites are the Correct the Celebrity classroom task in which you spot the grammatical errors in Justin Timberlake lyrics, Paris Hilton's blogs and various film titles, although I'm saddened by the fact that we can't just put a big red ring around Paris Hilton herself and fail her.
There are some good tips on writing clearly, some myths exploded about "bad" grammar, and overall it's good clean fun. It veers a little towards the prescriptive for my tastes (Why's there no discussion about dialect forms, for example?), but you can't win 'em all.