Machines are taking over the chat. That is, there are currently more posts by the feed bot than actual user activity. So, couldn't we drop the feeds that aren't security-related? We would also make the chat look more inviting and on-topic by not burying the rare signs of human activity between unrelated feeds.
xkcd feed: Other sites have democratically decided to remove the xkcd feed from their chats and I think the same arguments would work for the DMZ. The majority of xkcd strips isn't about security - and those that are could be posted manually.
SO Blog feed: It's nice to stay informed about the developments at SO but since new blog posts are also prominently announced in the sidebar on every page, it wouldn't be necessary to auto-post them in chat.
Do we want to keep having all xkcd strips and SO Blog articles auto-posted in chat?