I was surprised when I first heard that 50% of Europeans who attend WCA conferences are from Mainline denominations (as opposed to Evangelical). Many of the Americans from the Mainline denominations appear hostile toward Megachurches, so I wondered who these European attenders are and how they view Megachurches.
Recently I discovered this article which helped me get to know at least one of them a little better. Her name is Janet Chapman and she is a priest in the Anglican church. The article is a kind of travel log of her trip to the Leadership Summit in '04. It's charming and well written with some very astute observations and I've linked to it below.
Diary of Willow Creek.