Sometime around 2001 I created an online private music recommendation "club" with 20 friends and family. I called it the SongXchange. Originally executed with just email and FTP, a PHP-based version was eventually created by one of the group members. The gist of the club was that each group member would submit one favorite song per month, and those submissions (granular info about the song/group/album as well as a blurb about why you love it) would be sent out to everyone's email, one per day. The SongXchange ran successfully for around ten years.
It was so successful, in fact, that I explored the possibility of turning it into a full-fledged online business (note: this would have been during the heyday of MySpace, so social media was only barely a concept). RiffClick would make it easy for anyone to start and/or join a music recommendation club, and tracks would be pulled from an online database (similar to Spotify, Pandora, etc., though that would have been harder to pull off back then) for selection and listening by group members. Like millions of "cool" dot-com/app ideas before it, RiffClick was abandoned at the initial planning stage.
I still think it could've succeeded, though. :)
I only include this one for fun, really. While interning with Macromedia in 1996, I worked with a "special ops" Java-based team called JumpJet, let by Paul Madar (who went on to become a VP, though I don't recall if he made the transition to Adobe). We developed a number of on-the-cusp applications, including software that made it into the core graphics functionality of Netscape Navigator.
Anyway, the above is the only finished design of a project that didn't get a helluva lot of traction, though I feel like it was a viable concept: the Pumpstation (or Mediastation, an alternative name that might have avoided its early termination). This was essentially a small app that would house media "pumps" from different providers based on your preferences, actively displaying information on news, weather, entertainment, sports - you name it. Seems feasible, right? I kind of want to have it on my desktop right now.
Be sure to give the placeholder info a second glance. I was never much for ipsum lorem.