Google Video Search: Maybe not a dark pattern per se, but I theorise that Google deliberately provides a video search facility with poor UX, so that users will think 'I'll just use YouTube to search instead', thereby cutting off users from competitors' sites. I mean look how tiny the thumbnails are?
It might be useful to create a recognizable logo for the notion of a Dark Pattern so the concept can start to spread wider amount society and people can voice their opinion. It is hard to talk about something if you don't have a word to describe it yet. I made a quick mockup of a potential logo here