I have officially sold out, by enabling adverts on becontrary.com. I think I have made them quite subtle by using the same color scheme as the site and fitting them in to existing column sizes. There is a fine line between collecting some revenue to pay for expenses and scaring away the people that provide the content, so I would be interested in hearing peoples opinion on adverts in general.
Opinion on adverts? Okay: as long as they're not intrusive I ignore them, as soon as they start getting into my face too much (e.g. anything animated or too colourful) I adblock them. There's a certain ad/content ratio (about 75% ads) above which I run away from that site screaming, never to return.