I’ve seen those elsewhere. Way, way too intrusive IMO as it actually disrupts viewing and breaks interactive flow. I totally get why some site owners do it, the increases in advertising I've implemented here over the years, e.g. moving from the very small colour-matched text ad on the banner to the fairly large full-colour stuff we have now has made a huge difference to site earning potential and therefore my ‘wage’. It, along with eBay and Amazon, has turned what was a hobby into a fully viable business, but there is a line of intrusion I will not cross.
I very deliberately don’t use an ad blocker myself as I view them in the same way as Napster or whatever (they are similarly piracy devices enabling the user to get paid content without paying), but that said there are sites that just irritate the hell out of me (Allmusic, some of the newspapers like the Independent, a fair few forums etc) where the ads break the browsing experience to such a degree I don’t want to stay on the site beyond following a link, doing some very specific research etc. There is certainly a lesson webmasters can learn here; that too much advertising actively forces users away or tempts them to use a blocker and therefore deny you all ad income streams (obviously unless they are regulars who donate). It surprises me how few seem to grasp this.