Bettween

"Bettween is a #Twitter-based app that allows peepers, voyeurs or any curious person out there track any conversation between @users from the famous micro-blogging platform in an easy, clean and ordered way, even if you don't follow any of the participants of the conversation nor you're a Twitter member. People use Bettween to keep track of their own conversations with other people, or other people to track conversations from strangers"