Last winter I built an application called Subtweet that built on top of Twitter's Direct Message service, using Twitter's API as much as I could to reduce overhead. It is bittersweet that Twitter is improving DM as it makes Subtweet more and more unnecessary to users, but I am so happy to have all of these features built right in. I saw this shift coming when Twitter added multi-user DMing so I had already written the post mortem if anyone is interested.
http://subtweet.co/ http://chrisandrejewski.com/2015/02/07/subtweet-postmortem.h...