Hmm, I'd say that V22 Osprey does work. It's still a compromise and a full heli or full plane is better suited for most tasks but a hybrid does have its use.
http://www.defense-aerospace.com/dae/articles/communiques/AW...
I mean, you can certainly argue that the program was not worth the cost in money or lives lost (as is already being done in this subthread), but ultimately the thing works -- as someone who lives in San Diego, I see them flying overhead multiple times per week.
http://www.npr.org/2011/06/25/137414737/among-the-costs-of-w...