The Big Definition
Defining what exactly constitutes an Alternate Reality Game seems to be a very popular pastime to some. Interestingly enough, it often comes from people who, to me, really have no business attempting to define it at all, while being all to eager to do so (which is the subject for another evening and a bottle of brandy). One of the few people who I believe to be uniquely qualified, Sean Stacey (founder of Unfiction and co-puppetmaster for Project MU/Metacortechs), has just published a pretty nifty essay on the subject.
While I still subscribe to the notion that a good ARG is, at it's core, a form of internet archaeology, Sean does a great job quantifying many of those troubling nuances that plague those attempting to pin a definition down.
Anyway, for all you meta-heads out there (and you know who you are!), enjoy!