Oh, Lord, there are soooooooooooo many. Busker Alley, Ghost Brothers of Darkland County, Arthur the Musical, Mask the Musical, Happy Days the Musical... What these shows generally have in common is that they aren't very good (but no worse than many flops that make it to Broadway) and are really terribly produced.
The NY Times had a long article on the topic back in January.
As for a new projected timetable, the producers — who started out aiming for 2010 before moving the dates again and again — are opting not to offer any this time around.
“We plan on continuing to develop the musical and will be excited to share the news when we are ready,” Mr. Sanders said by email. “As any magician knows, you never show how the illusion is made real.”
Sheryl Crow's Diner is still floating around. It was performed at Signature in DC over the winter. Up next is a production in Delaware. http://delawarepublic.org/post/new-musical-sheryl-crow-and-barry-levinson-coming-delaware
Omg I actually saw happy days the musical at papermill years ago when I was like 12. It was awful. All I rember is colored toilet plungers at the end lol