If there was a list I think you'd be able to count its items on both hands. I believe there's a big backlog with the review process at the moment but looking at some recent updates to big apps (Skype, for example) you shouldn't get too excited about them fully supporting the new screens yet. In this case, Skype have said there'll be another update next month. I use my iPhone a lot for podcasts and Twitter; Tweetbot, Pocket Casts, and Instacast look pretty bad on the 6 Plus. As a result I've been using Overcast for my podcasts (which I'm really starting to like) and just dealing with Tweetbot because the alternatives (even the official Twitter app which has been updated) are pretty inferior in my opinion. I'm sure many developers are working hard and that we'll see updates pretty soon. That time can't come fast enough.