Where were you while we were getting high?

How do you measure the size of a fandom? In the debates sparked by the recent fannish migration to the Merlin fandom, there were again talk about fandoms that eat other fandoms. Now I don't think anyone would doubt Harry Potter was one of those. And maybe Star Wars, Lord of the Rings and Smallville. But what about other fandoms, perhaps medium-sized ones? Do you measure them in terms of the sheer number of fics/art/crafts/fanmixes/podfics produced? The number of people registered for a fandom-specific discussion board/joined a fandom-specific community or the proportion it takes up in multi-fandom venues? The number of discussion posts? Does the quality of the fics or posts count? There are loads of lurkers in fandom, do they count, and if yes, how do they count?

I know it's stupid to obsess about the size of a fandom when, I guess, the only reason it would matter is for justifying why you're writing about that fandom in an academic paper. But I just can't get it out of my head.

I know it's tempting to try out new things. I know you may think the song really fit the story - may enhance the story, even. But do you really have to have the song as the background music of the podfic? Not all podfics are easy to the ear. Background music (esp. songs with words), as a rule, does not help, at all.

It's a bit mind-boggling that Supernatural, a show that doesn't intend to be complex/deep (unlike perhaps BSG?), has inspired so much meta that it actually has a meta community (spn_heavymeta).

There seems to be a lot of meta on slash on metafandom alone. But what does het meta look like?