Markfolder was released as an early access version just over a month ago. Its goal is to help Twitter users organise tweets they want to save/bookmark, by giving them the ability to group tweets with folders.
Still in its "early access" version, users have already saved over 500 tweets.
Even though there are now 30 signed up users, the bulk of the bookmarks have been saved by just 3 "power users". These guys are prolific in the bookmarking!
The next stage is to release a mobile version of Markfolder. Since 80% of Twitter users are on mobile, this is sorely needed.