In my years over at Flickr I've noticed that Explore can explode a users view count, and add a ton of users even days past the upload date. I personally think a lot of the people that give the congrats comments are just trying to siphon off some activity to their own page. Explore can often seem quite confusing, but I've noticed certain users that I follow have a very specific upload schedule that consistently gets photos into that group and helps accumulate a ton of views. Specifically uploading in the early morning, especially in bad weather when more people seem to look for things to do inside. The "unknown source" for views has always been a strange source, but I'm not sure what it could be connected to. I think I read something a long time ago about "bots". I don't really care about the views too much, but I do appreciate the informative feedback on that site, especially to the shots I post that have some kind of historical background. I used to get a lot of negative feedback but that has dwindled down in recent years.